Trying to add new card but it keeps declining.

When we I add a payment method or edit or put a new one

See -> Change, add or remove Apple ID payment methods

Change, add or remove Apple ID payment methods – Apple Support (UK)

• Add first the new card, then remove the old one.

Click here for more support and assistance.

You do need to follow the instructions and contact Apple support. We are all other users and do not have access to accounts or any records.