I need to change my card details

This is primarily a user-to-user support forum; other Apple users like you.

There is a link to contact Apple support at the top right of this page or you can use the following to call them: Contact Apple for support and service - Apple Support

Log into your account in the App Store/iTunes and you should be able to change/verify it there. Or you can click the blue Edit payment methods in the article below. When signed in and the page loads, you will be on the credit card page. After updating that, click the Go Back button at the lower left and you will be on the address page. If you have a subscription, you need to add the new card, and then promote it to the primary payment method before you can remove the old card.

Apple ID payment information - change.  *

I want to reinstate my method of payment for apple's automatic pay. I don't see where I can reinstate the original payment method.