How to add credit card

Apple support's article: Set up Apple Pay

says how to:

"Add a new card on your iPhone

In the Wallet app, tap the Add button Tap Debit or Credit Card.

Tap Continue.

Follow the steps on the screen to add a new card.

 If prompted, choose your bank or card issuer from the list or find them using the search bar.

Verify your information with your bank or card issuer. They may ask you to provide additional information or to download an app before approving your card for use with Apple Pay.

All the best :-)

asiya128 Said:

"How to add credit card in wallet"

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Troubleshooting Adding a Method of Payment:

Use a Computer:

When troubleshooting Methods of payment, as it would be more user friendly doing do.

Sites to Use:

• Change, Add, or Remove Apple ID Payment Methods - Apple Support. See if you can manage your method of payment there.
• Payment Methods that you can Use with your Apple ID - Apple Support. See if your method of payment is an option in your location.

No Success?:

For Financial Assistance, Contact Apple Store Support:

You need to contact Apple Support Directly. This is a User-to-User forum. We are all volunteers. So, as you may suspect, no one here has access to that information — and that is a good thing, BTW. That’s why for Financial Assistance, you need to contact Apple Support. They’ll see what’s going on and will run you through the fix.

Apple Contact Info:

• Contact Us - Choose Locations
• Proceed from there, as necessary
• Why the Wait: Phone calls are taking a bit to go through at the moment, due to lots of calls. With the Coronavirus Pandemic, many are at home at the moment, with much time on their hands to contact Apple. So, just stay on the line, and you will get through :)