I have been in the process of switching banks. Yesterday, my debit card for my new account arrived, and I was happy to add it to Apple Pay and test it out. However, the transaction declined. To make a long story short, I fixed the issue, with no useful assistance from Apple Support. Here's how to resolve Apple Pay issues.
1. Whenever you add a new credit or debit card to Apple Pay, you will always be prompted to verify your identity with a text code, phone call, or email. Typically, verification is best done through text, because you can grab the code without having to go into Messages. If you are not prompted to verify your identity, disconnect the card from Apple Pay and follow the steps below.
2. Delete the banking app or credit card app that's associated with the card you are attempting to add to Apple Pay. Sometimes, app updates don't install correctly. You will need to reinstall your banking or credit card app you are using with Apple Pay.
3. Restart your iPhone.
4. Reinstall your banking app or credit card app. Yes, you can use Apple Pay without having your banking app or credit card app installed, but if you have online banking and or credit card access, you might as well use it, especially for the cashback rewards.
5. Log into your banking or credit card app.
6. Use either the Wallet app or your bank or credit card app to add the card to Apple Pay. "upon completing verification, you will receive a message from the Wallet app that your card is ready for Apple Pay. However, if you use your banking or credit card app to activate your card on Apple Pay, different financial institutions differ as to how they present to you that your card is ready for Apple Pay. While you will still receive confirmation in the Wallet app, how your bank or credit card app communicates will vary. For example, while Wells Fargo, U.S. Bank, or Chase will let you know that your Apple Pay is activated through the financial institution end, Capital One will state that your debit card isn't eligible for Apple Pay, which is not accurate. As long as the verification is completed, you can disregard the message from Capital One stating to the contrary. I hope that this helps.