Why won’t you let me update my billing info??

So I wanted to update an app I already had on my phone, but it keeps prompting me to update my billing info stating that my card has been declined? Which is ********, but none the less I logged into my account thru the apple website to change my payment method to “none” so I could save it and try to reeenter this card to see if that works (annoying)... however, when I change the payment method to “none” and click “save”. It KEEPS GIVING ME A MESSAGE SAYING “CAN’T UPDATE PAYMENT METHOD”. ***?????