Cannot verify child account with credit card

I have been unable to verify my child's new minecraft account with using my credit card. I have tried four different cards on multiple days and all attempts return an error message. I've emailed my bank and mojang, with no response. I have used multiple browsers on different devices. I have notified my bank of purchases from Sweden. I have seen multiple other people report similar issues while trying to verify an account for a child. I realize this is not a game based bug, but it appears to be a larger systemic issue.