What should I do if I encounter payment errors while applying for a Vietnam visa online?

The user faced repeated payment errors while trying to pay for a Vietnam visa application online, despite correctly filling out the form and using two different cards. They discovered that the issue stemmed from a mismatch in the address entered on the website, which triggered fraud monitoring on their cards. The problem was resolved by temporarily disabling the fraud monitoring with their bank. Other users commented on similar issues, suggesting potential website downtime and advising caution due to possible double payments.