Card invalid, the card I have been using for years is now invalid, got a new card and still have the same problem. No access to orders that are waiting to be shipped . HELP!

I have the following message showing up when I log in:

Unable to charge

Amazon is not able to charge with the listed charge methods. This could be either due to incorrect details or lack of bank’s permission for respective marketplace.

I got a new card today and added it as the charge method, still no change.

It is a business debit card. The old one was Visa, the replacement is Mastercard.

I use the previous card for years with no issue. The new card was issued by my bank (Natwest) before the old one was due to expire.

It’s all very strange and I have no idea what to do. Seller support are telling me I need to add a credit card, which I don’t have. I have orders waiting to be shipped but I have no access to my account as it wont let me past the error message.

I’m sure the next thing will be my account is punished for the late dispatch of these orders which is always fun.

Please help!