OK, first I will say that the mistake was mine. I was making reservations for a trip to the UK this summer through Booking.com, and I accidentally pushed the button for a non-refundable room rate at Pullman Hotel St. Pancras. I didn't realize it until a week later, when I had to change my visit to London to the beginning of the trip rather than the end. I called Booking.com, told them my error and asked if they could negotiate a move to earlier in July (there are rooms available—I checked) and of course I expected to pay an upcharge. No dice. It is hard for me to understand why the hotel's policy is so punitive, as the difference between non-refundable and refundable is not that great. I also contacted the hotel directly, and they wouldn't budge. Leaves a bad taste, to say the least.