There are a few reasons that payments may not go through.
Fraud Checks (payment provider)
Our payment provider uses a sophisticated machine learning system to try to prevent fraudulent cards being used. They check a number of factors, such as frequency of payments across their network, to country of origin and many others.
'do not honor' / Other
Occasionly the bank or credit card processors (VISA/Mastercard etc) employ their own fraud checking systems, and may reject the transaction.
Cardholder Address mismatch
If the address details you enter on the payment page do not match the cardholder address, your payment may fail.
This can be especially problematic on commercial/corporate payment cards that do not have a clear registered cardholder address or holder.
Unfortunately we do not always have visibility in to why a transaction did not go through.