Forget rebooking ask for a refund. A soft Diamond benefit, IME. Had one last weekend, i cancelled at 7 pm, the clerk at the front desk couldnt do it for me, but said call back tomorrow and ask for the manager, who did a refund promptly and cheerfully, thanking me for my loyalty. When I cancelled i did check to make sure they still had rooms available for booking, becuase if sold out I dont think asking is reasonable.