Originally Posted by
plunet
Do either of these cards have SCA (Strong Customer Authentication) enabled by your bank where you get a one time passcode for online purchases? If they don't, and knowing how the US banking sector is rarely keeping pace with the rest of the world, then this could be the problem - the payment provider for the Vietnam government probably requires SCA and if the card issuing bank doesn't support it then it fails.
In this case, there are two options.
1. Ring the bank that issued the card, ask them to check for failed transactions, and ask if they can do a manual pre-auth for SCA for this failed transaction and then try again.
2. Find a bank card that supports SCA. Typically from a challenger/digital bank with modern backend systems.
I suspect you were correct. (re 2) CapitalOne seems to support SCA and I got a text with a code which allowed the transaction to complete when she tried my CapitalOne card. (re 1) Unfortunately, she did call the bank twice and they did not see any failed transactions. It is possible that if the bank doesn't support SCA, maybe they never see it?