Something similar to me happened at Ritz Kyoto where they had a French or Italian restaurant on-site and listed as a participating one. When I asked for the bill and 20% discount with the printed list, the server was confused and had to ask the manager. Then the manager came over and give me a small card which lists all the dates excluded from the discount. It was like using a best buy coupon where the exclusion are so extensive it would be better to just list the available dates, basically blacking out high season months and all weekends. I got quite angry since the only reason I would dine there was for the 20% discount or there would tons of other options in Kyoto. The manager apologized and offered a beer charge waived from the bill which was a ridiculous $10 off a $500 bill. In the end we met half way, but it shows how disorganize Marriott is. The manager said they have no control over the website and the offer is not updated frequently, but that is no way a customers fault. I even mentioned to the manager this is a shady practice and false advertising and informed Ritz Kyoto management.
I learned my lesson, always ask before making a reservation.