I had an interesting experience canceling a reservation at the Regent's Park Marriott in London. When I tried to cancel online, it would not issue a cancellation number and when I tried through the plat dest, they said since it was manually entered by the hotel, only the hotel could cancel the reservation. So I call the hotel, and the guy cannot cancel the reservation either - he has to email someone at the rate guarantee office to cancel (he had no phone number for them)! Anyway, it was canceled a day later, but it does take some doing. Is this a standard problem with US reservations, or just UK?

Just to add the rate info:

Marriott.com: 155 GBP
expedia.co.uk: 109 GPB
final rate: 81.75 GPB