"I am unable to add charge method to my amazon account"

First, is it your account or are you just an authorized 'other party'?

Go into your account details and see if everything is as it should be. Sometimes accounts get hacked!

Then try this -- This is my standard credit card template so use what applies!

Amazon is weird on so many levels and this seems to work at least sometimes!

First, be sure it is an actual CREDIT Card. While Amazon claims that a Debit Card will work, that is seldom true! They WILL charge a Debit Card for initial fees but they will NOT take it on continuing basis most of the time despite their claims!

Put the card number into your BUYER side account first. Wait an hour (sometimes less) for the gerbils to work their way through the system and then put it in the SELLER side.

There was one recent response from a seller on a post that they DELETED the card that was on the buyer side and put the SAME card back in after a little bit and it fixed the problem. Amazon is a maze of broken links in their antiquated software.

Here is a thread where the OP says it worked.

https://sellercentral.amazon.com/seller-forums/discussions/t/096ef5b2-ffd5-4943-86fe-41c9d087a7e7?postId=0fbb2fae-1e92-4c41-bdb5-80851137886b