While looking for a hotel in Mannheim, the site continuously kept popping up warnings of "last few rooms left" at most hotels and that I should book something ASAP at no risk if I had to change things, due to no cost cancellation. So booked hotel as backup then tried to cancel, when I found a more suitable hotel( our requirements changed slightly) Despite doing this within an hour of original booking, I was told there was no refund and full amount would have to be paid. Booking.com say that the "hotels" can change their booking conditions at will. So you might think your booking with no cancellation charge but only find out this is not so when you try to cancel. BE WARNED.