It's really baffling me! It first happened a couple of months ago, I tried to place an order and they refused my payment. I had money in the bank, my card is the same one I've had since 2020 and it doesn't expire until 2025. I'd paid for Amazon Music and Kindle Unlimited a couple of days before this. I contacted Amazon and they said my bank refused it because my card was expired (even though it's not). So I contacted the bank (I'm with Nationwide) and they gave me the same response, they suggested to remove my card and then put it back in the next day. This worked. Until the next time I tried to place an order a couple of weeks ago! I tried everything I tried last time and nothing worked. I gave up and forgot about it.
Until just now when I tried to order something and the payment was refused again!! Even though since the last time it was refused, Music and Kindle have been paid for 
It's so frustrating!! Amazon is the ONLY place it seems to be refused, my card works everywhere else!
Has anyone else had this problem? Fwiw my husband is also with Nationwide and has never had any issues on his account 🙄