I thought, that you in the US had a 30 day period (after the card has been charged) to refuse and than the hotel/car-rental-company etc had to proof "the contrary".

Unfortunately this is not the legal situation in Switzerland - but still, when I had, 2 years ago, a double charge of a Las Vegas Hotel, I phoned Diners Club Switzerland, they did immediate credit me, and 1 month later they reported, that the matter hase been settled with the hotel.

But nevertheless I decided yesterday, that I will NOT presigne without amount anymore.