I have flown AirAsia about 10 times now, I think I have booked directly at AirAsia.com twice.

I often use UnionPay and their UnionPay payment screen is broken. When I try to book with my American Visa card, my bank always blocks the initial attempt, they call me, I tell them I approve of the charge, than I reattempt to book, and because my card was declined once, AirAsia will not accept it.

I usually just end up booking third party. I spent like an hour trying to book through their webiste in December, before breaking down and using Ctrip.