Tag not monitored by Microsoft.
These are possible reasons: Troubleshoot a declined card
I will recommend you take a look at the above link to fix the issue.
However, if that does not work you will need to create a support request with the billing team. See:
https://azure.microsoft.com/en-us/support/create-ticket
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola