I tired last week in Dallas at a Doubletree as I needed to leave 1 day early from a 5 day stay. I called Diamond desk but was refused. I spoke to supervisor and he would not move. I even offered to pay the full rate (it was $10 extra per night) and he refused this. I doubt whether I would use the net direct again because it is so rigid. Pretty disappointed with Hilton customer service and comprehension. Stayed over 80 nights this year alone so you expect some give and take.