I spent 4 years working in the credit card dispute/chargeback department for a bank. Shaggy_mutt is correct, it is the Visa & Mastercard rules and regulations that apply to the merchants. It has been a few years since I worked in the industry, but when I did, travel related disputes (airline, car rental, hotel) charges were always harder to chargeback, as the rules generally seemed to favor the merchant. Also, foreign merchants were generally harder to charge back, as the international rules and regulations were different than the domestic ones. I would not be suprised if you end up stuck with the fee, as the fact that there was a cancellation fee was disclosed, even if the exact amount or percentage was not. Depending on how much money your credit card company makes off of you, if you continue to push the issue, they may consider writing the $500 off as a courtesy to you, but YMMV on that one.