Stella, Firstly, the card information should be double-checked, including the card number, expiration date, and security code, ensuring that the billing address matches the one on file with the credit card company. If the card information is correct and the issue persists, the next step is to contact the credit card company to confirm any holds or suspicious activity on the card. If necessary, try using a different payment method such as a different credit card. If none of these steps work, contact with Amazon customer service they will better help you to find out the exact reason of why your credit card is invalid.
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