有關 airasia 訂機票事宜

i think you can describe a bit on the error (ie error message/error code) then will be easier to help you
when you process a payment online, usually they need to process the security check either via the VVS code (3 digits code that printed at the back of your credit card) or you have to have the Verified by Visa, and as for this, if you are using HSBC's visa card, you have to first go to HSBC online banking, then log on to your profile, and under the Cards section, at the right hand side, you will see an icon Verified by Visa - Registration .... go register frist and try to process the payment again and see
If you still have other questions/problems on the payment, you can try to describe a bit further and will try to help you out again

我都係在airasia 買機票。一d問題都無。

visa 俾錢時，要填張卡背面的三個數字，你有無填錯？

若否，就要試多幾次。唔得我都唔知lo。