And as shocking as it may seem to some, refunding a transaction even in full does not absolve the contractual obligation. This is a common misconception about the law but a merchant can refund you something you bought because it believes it was mistake that you ought have known or any reason merchant claims, such as unproven fraudulent transaction. But that doesn't end its legal obligation towards you. A contract creates an obligation and it is not absolved just because the merchant processed a refund unless that's what both of you agree to. You can still suffer injury despite a full refund, as was the case of the couple stranded in Portugal demonstrated or the event promoter whose business was almost wrecked by the untimely cancellation of the tickets he bought for the artists on tour.

AC's ToC can be challenged, don't assume it can be easily challenged but know it can be challenged. If AC ToC conflicts with an applicable law which AC is bound to, then the law will supersede the ToC.