I ran into this problem last year at the Fairmont Tremblant, trying to redeem $25 x 4 certs. Desk agent got the front desk manager who was insistent they were in CAD. I even had printouts of the T&Cs from the FPC website stating the certs are in USD. I called FPC on my cell phone, passed it to the front desk manager, where FPC explained to him directly that they are in USD. He then asked FPC to send him an e-mail confirming as much. They eventually credited me in USD, but it shouldn't take that much work.
I later send an old fashioned snail mail letter to FPC, with cc to the hotel GM, requesting that they do a better job of educating the properties on the currency of their certificates.
I received replies from both FPC and the hotel, with the hotel offering of a free dinner on our next visit for our troubles.
I think they eventually got it right, but you shouldn't have to fight with the hotel staff to get them to agree to the terms of their own programs.