Try this:
1.
Sign in to your Apple ID account page and edit / update your Apple ID details.
https://appleid.apple.com
- On the Sidebar click Payment methods -> then tap Payments Methods and tap Manage payment method.
2.
Or -> Add a payment method to your Apple ID
Add a payment method to your Apple ID – Apple Support (UK)
- If you want to change your card, you need to add first the new card, then remove the old card.
3.
See -> Remove a payment method from your Apple ID
Remove a payment method from your Apple ID - Apple Support
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If you can't remove a payment method
If you have subscriptions like iCloud+, have an unpaid balance, or you use purchase sharing, you must keep at least one payment method on file.
4.
See also -> Payment methods you can use with your Apple ID
Payment methods you can use with your Apple ID – Apple Support (UK)
fyi: Not all credit & debit cards seem to work with App Store / iTunes Store, try a different one, or preferably a credit card. If your card is not accepted as a paymenf method, you need to contact your bank.
Click here for more support and assistance.