I had trouble trying to pay for a ticket with them last year, so I ended up going to one of their local sales offices here in Mexico City. They wanted to charge me a $25 fee, but a manager agreed to waive it, given that their site would not accept my perfectly valid non-Mexican CC.

On board the plane, I've been happy with AM (and I like their lounges too), but dealing with their customer service department can be a pain. (I discovered after a few attempted exchanges with their CS people that I knew more about their operations than many of their agents do. Guess they're not trained properly.)