Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Where are you entering the new debit card number?
Entering your information in the right form or place or page, is quite vital.
I advise you to go to your Amazon.com account, on a web page or on a web browser.
Log into your Amazon.com account as needed.
Go to Your Account
then to the Payment section
then click on Add a Credit or Debit Card
then follow the directions on-screen.
Note: try entering the address info for the new debit card, exactly as your address is shown on your debit card account statement from your bank. That is, most likely, how that address is stored in their computers, and your new debit card's information has to match what the bank stored for your information, for it to be accepted.
Let me know if you run into any difficulties.