Yes, we agree that disclosure is the issue here. The confirmation really should have included the necessary information or at least a link to the T&Cs that contained it. We can't say whether it did not or not (maybe the OP can confirm), but in any case it boils down to whether the information was adequately communicated. Avis clearly feels that it was. The credit card company might feel differently. I don't think that a claim would necessarily be baseless, but it would really depend on how the confirmation and/or reminder email was worded in our opinion.