diff --git a/frontend/src/lib/components/admin/HolidayHours.svelte b/frontend/src/lib/components/admin/HolidayHours.svelte
index 0be68e0..5c46c36 100644
--- a/frontend/src/lib/components/admin/HolidayHours.svelte
+++ b/frontend/src/lib/components/admin/HolidayHours.svelte
@@ -1,9 +1,11 @@
 <script lang="ts">
 	import { SvelteDate } from 'svelte/reactivity';
 	import { toast } from 'svelte-sonner';
-	import { sanitizeText } from '$lib/utils/toast-safe';
+	import { extractErrorMessage, sanitizeText } from '$lib/utils/toast-safe';
 	import { apiFetch } from '$lib/utils/api';
-	import { range } from '$lib/utils/format';
+	import { range, formatDuration } from '$lib/utils/format';
+	import { formatUserName } from '$lib/utils/nameDisplay';
+	import { parseWallClockDate } from '$lib/utils/timeSlots';
 
 	// shadcn-svelte components
 	import { Button } from '$lib/components/ui/button';
@@ -33,6 +35,30 @@
 		hours: WorkingHourRow[];
 	};
 
+	type OverlappingBooking = {
+		id: string;
+		start_time: string;
+		duration_minutes: number;
+		status: string;
+		user: {
+			id: string;
+			full_name: string;
+			email: string | null;
+			phone: string | null;
+			previous_first_name?: string | null;
+			previous_last_name?: string | null;
+		} | null;
+		services: string[];
+	};
+
+	interface Props {
+		openUserModal?: (userId: string) => void;
+		openBookingModal?: (bookingId: string) => void;
+		rescheduleVersion?: number;
+	}
+
+	let { openUserModal, openBookingModal, rescheduleVersion = 0 }: Props = $props();
+
 	// =============== State ===============
 	let exceptionGroups = $state<ExceptionGroup[]>([]);
 	let exceptionGroupsLoading = $state(true);
@@ -61,7 +87,10 @@
 	});
 
 	const isFormValid = $derived(
-		exceptionDraft.name.trim() !== '' && exceptionDraft.weekStarts.length > 0
+		exceptionDraft.name.trim() !== '' &&
+			exceptionDraft.weekStarts.length > 0 &&
+			!hasOverlap &&
+			!checkingOverlap
 	);
 
 	function validateNameField() {
@@ -91,6 +120,51 @@
 
 	const dayNames = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'];
 
+	// =============== Conflict Resolution State ===============
+	let overlappingBookings = $state<OverlappingBooking[]>([]);
+	let checkingOverlap = $state(false);
+	let hasOverlap = $derived(overlappingBookings.length > 0);
+
+	async function checkConflictingBookings() {
+		if (exceptionDraft.weekStarts.length === 0) {
+			overlappingBookings = [];
+			return;
+		}
+
+		checkingOverlap = true;
+		try {
+			const payload = {
+				weekStarts: exceptionDraft.weekStarts,
+				proposedHours: exceptionDraft.hours.map((h) => ({
+					weekday: h.weekday,
+					startTime: h.start_time,
+					endTime: h.end_time,
+					isOpen: h.is_open
+				}))
+			};
+
+			const response = await apiFetch('/api/admin/bookings/conflicting-for-exception', {
+				method: 'POST',
+				headers: {
+					'Content-Type': 'application/json'
+				},
+				body: JSON.stringify(payload)
+			});
+
+			if (response.ok) {
+				const data = await response.json();
+				overlappingBookings = data.bookings || [];
+			} else {
+				overlappingBookings = [];
+			}
+		} catch (err) {
+			console.error('Error checking conflicting bookings:', err);
+			overlappingBookings = [];
+		} finally {
+			checkingOverlap = false;
+		}
+	}
+
 	// =============== Helper Functions ===============
 	function weekdayLabel(i: number) {
 		return dayNames[i];
@@ -167,8 +241,8 @@
 							}) => ({
 								id: h.id,
 								weekday: h.weekday,
-								start_time: formatTime(h.startTime),
-								end_time: formatTime(h.endTime),
+										start_time: h.startTime,
+										end_time: h.endTime,
 								is_open: h.isOpen
 							})
 						) || []
@@ -224,7 +298,7 @@
 				await fetchExceptionGroups();
 			} else {
 				const text = await response.text();
-				toast.error('Failed to create: ' + sanitizeText(text), { id: loadingToast });
+				toast.error('Failed to create: ' + sanitizeText(extractErrorMessage(text)), { id: loadingToast });
 			}
 		} catch (err) {
 			console.error('Error creating exception group:', err);
@@ -255,7 +329,7 @@
 				await fetchExceptionGroups();
 			} else {
 				const text = await response.text();
-				toast.error('Failed to delete: ' + sanitizeText(text), { id: loadingToast });
+				toast.error('Failed to delete: ' + sanitizeText(extractErrorMessage(text)), { id: loadingToast });
 			}
 		} catch (err) {
 			console.error('Error deleting exception group:', err);
@@ -281,6 +355,7 @@
 		};
 		weekRangeFrom = '';
 		weekRangeTo = '';
+		overlappingBookings = [];
 	}
 
 	function createNewException() {
@@ -288,6 +363,18 @@
 		showExceptionModal = true;
 	}
 
+	// Check for conflicts whenever weekStarts, hours, or rescheduleVersion change
+	$effect(() => {
+		// Track these reactive values so the effect re-runs when they change
+		const weekStarts = exceptionDraft.weekStarts;
+		const hours = exceptionDraft.hours;
+		const rv = rescheduleVersion;
+		// Avoid triggering check on initial empty state
+		if (weekStarts.length > 0 && showExceptionModal) {
+			checkConflictingBookings();
+		}
+	});
+
 	function addWeekRange() {
 		if (!weekRangeFrom || !weekRangeTo) {
 			toast.error('Please select both start and end dates');
@@ -353,7 +440,7 @@
 					<p class="col-span-2 text-sm text-gray-500">No exception groups found.</p>
 				{/if}
 
-				{#each exceptionGroups as g (g.weekStarts)}
+				{#each exceptionGroups as g (g.id)}
 					<div class="group relative h-full rounded-lg border p-4 transition-all">
 						<div class="flex h-full flex-col gap-3">
 							<div class="flex-1">
@@ -601,6 +688,100 @@
 			</div>
 		</div>
 
+		<!-- Conflict Resolution -->
+		{#if checkingOverlap}
+			<div class="flex items-center gap-2 px-4 pb-4">
+				<svg
+					class="h-4 w-4 animate-spin text-gray-500"
+					xmlns="http://www.w3.org/2000/svg"
+					fill="none"
+					viewBox="0 0 24 24"
+				>
+					<circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4" />
+					<path
+						class="opacity-75"
+						fill="currentColor"
+						d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z"
+					/>
+				</svg>
+				<span class="text-sm text-gray-500">Checking for conflicting bookings…</span>
+			</div>
+		{:else if hasOverlap}
+			<div class="mx-4 rounded-lg border border-amber-200 bg-amber-50 p-4">
+				<div class="mb-3 flex items-center gap-2">
+					<svg
+						xmlns="http://www.w3.org/2000/svg"
+						class="h-4 w-4 text-amber-600"
+						viewBox="0 0 24 24"
+						fill="none"
+						stroke="currentColor"
+						stroke-width="2"
+					>
+						<path
+							d="M10.29 3.86L1.82 18a2 2 0 0 0 1.71 3h16.94a2 2 0 0 0 1.71-3L13.71 3.86a2 2 0 0 0-3.42 0z"
+						/>
+						<line x1="12" y1="9" x2="12" y2="13" />
+						<line x1="12" y1="17" x2="12.01" y2="17" />
+					</svg>
+					<span class="text-sm font-medium text-amber-800">
+						{overlappingBookings.length} booking{overlappingBookings.length > 1 ? 's' : ''} conflict{overlappingBookings.length >
+						1
+							? ''
+							: 's'} with the proposed hours
+					</span>
+				</div>
+				<div class="space-y-3">
+					{#each overlappingBookings as booking (booking.id)}
+						<div class="rounded-md border border-amber-200 bg-white p-3">
+							<div class="min-w-0">
+								<div class="text-sm font-medium">
+									{formatUserName(
+										booking.user?.full_name || 'Unknown',
+										booking.user?.previous_first_name,
+										booking.user?.previous_last_name
+									)}
+								</div>
+								<div class="text-xs text-gray-500">
+									{parseWallClockDate(booking.start_time).toLocaleTimeString('en-GB', {
+										hour: 'numeric',
+										minute: '2-digit',
+										hour12: true
+									})}} ·
+									{formatDuration(booking.duration_minutes)}
+									{#if booking.services?.length}
+										·
+										{booking.services.join(', ')}
+									{/if}
+								</div>
+							</div>
+							<div class="mt-2 flex gap-2">
+								{#if openBookingModal}
+									<Button
+										variant="outline"
+										size="sm"
+										class="h-7 text-xs"
+										onclick={() => openBookingModal(booking.id)}
+									>
+										View Booking
+									</Button>
+								{/if}
+								{#if openUserModal && booking.user?.id}
+									<Button
+										variant="outline"
+										size="sm"
+										class="h-7 text-xs"
+										onclick={() => openUserModal(booking.user!.id)}
+									>
+										View Client
+									</Button>
+								{/if}
+							</div>
+						</div>
+					{/each}
+				</div>
+			</div>
+		{/if}
+
 		<Modal.Footer class="flex items-center justify-end gap-2">
 			<Button
 				variant="outline"
@@ -705,10 +886,10 @@
 											</span>
 										</td>
 										<td class="py-2 text-sm">
-											{row.is_open ? row.start_time : '—'}
+											{row.is_open ? formatTime(row.start_time) : '—'}
 										</td>
 										<td class="py-2 text-sm">
-											{row.is_open ? row.end_time : '—'}
+											{row.is_open ? formatTime(row.end_time) : '—'}
 										</td>
 									</tr>
 								{/each}
diff --git a/frontend/src/lib/components/admin/TimeBlockers.svelte b/frontend/src/lib/components/admin/TimeBlockers.svelte
index 4751d9e..30389f1 100644
--- a/frontend/src/lib/components/admin/TimeBlockers.svelte
+++ b/frontend/src/lib/components/admin/TimeBlockers.svelte
@@ -3,7 +3,7 @@
 	import { apiFetch } from '$lib/utils/api';
 	import { CalendarDate } from '@internationalized/date';
 	import { toast } from 'svelte-sonner';
-	import { sanitizeText } from '$lib/utils/toast-safe';
+	import { extractErrorMessage, sanitizeText } from '$lib/utils/toast-safe';
 	import { formatDuration, range } from '$lib/utils/format';
 	import { formatUserName } from '$lib/utils/nameDisplay';
 	import { formatLocalDateTime, parseWallClockDate } from '$lib/utils/timeSlots';
@@ -410,7 +410,7 @@
 							},
 							body: JSON.stringify({
 								start_time: startIso,
-								duration_minutes: 60,
+								duration_minutes: booking.duration_minutes,
 								description: `RESERVATION:placeholder:${booking.id}`
 							})
 						});
@@ -440,7 +440,7 @@
 				await fetchBlockers();
 			} else {
 				const text = await response.text();
-				toast.error('Failed to create: ' + sanitizeText(text), { id: loadingToast });
+				toast.error('Failed to create: ' + sanitizeText(extractErrorMessage(text)), { id: loadingToast });
 			}
 		} catch (err) {
 			console.error('Error creating time blocker:', err);
@@ -467,7 +467,7 @@
 				await fetchBlockers();
 			} else {
 				const text = await response.text();
-				toast.error('Failed to delete: ' + sanitizeText(text), { id: loadingToast });
+				toast.error('Failed to delete: ' + sanitizeText(extractErrorMessage(text)), { id: loadingToast });
 			}
 		} catch (err) {
 			console.error('Error deleting time blocker:', err);
diff --git a/frontend/src/routes/admin/+page.svelte b/frontend/src/routes/admin/+page.svelte
index 599dce7..3eb2a6a 100644
--- a/frontend/src/routes/admin/+page.svelte
+++ b/frontend/src/routes/admin/+page.svelte
@@ -378,7 +378,7 @@
 			{#if sectionState.scheduling === 'expanded'}
 				<div class="space-y-4 p-4">
 					<TimeBlockers {openUserModal} {openBookingModal} {rescheduleVersion} {defaultHours} />
-					<HolidayHours />
+					<HolidayHours {openUserModal} {openBookingModal} {rescheduleVersion} />
 					<WeeklySchedule {defaultHours} />
 				</div>
 			{/if}