If your payment was declined, one of the most common reasons is Do not honor - financial jargon for "The payment was declined by your card issuer, and they won't tell us why".
To prevent this from happening again, call your card issuing bank, tell them that the transaction was declined by them (you can mention "error code 05 - do not honor") and ask them to allow future payments with Coinmama.
After they confirm that future payments will go through it is recommended to wait 30 minutes before placing a new order.
It is also important to make sure that:
- You entered the correct CVV code (the 3 digits on the back of your card)
- You've entered the correct billing information
- The card is approved for international/online purchases
- There are sufficient funds available
- The card is not expired or canceled
- The card has not been reported stolen or lost
Alternatively, you can always try with a different card, as that may also do the trick.
PS: If you don't have the number of your card issuing bank, it may show on the back of your card.