Copa's system is well known to be fraught with problems. Double billing, non-billing, authorization without subsequent billing, and a lot more. I fly Copa all the time because I have no choice. But I always buy my tickets at an online agent (Orbitz, Expedia, Priceline) because you can often get better prices online than at Copas website (Copa guarantees your purchase is "secure", but not the lowest price for the ticket) and when you buy from an online travel agent you often get a 24 hour window to cancel and refund, whereas when you buy from Copa direct, the minute you gave them the money, you're lucky to be able to do any changing without a penalty, and many tickets are directly nonrefundable.