I can’t edit my payment information and my iOS is up to date

These are the instructions:--> Change, add or remove Apple ID payment methods – Apple Support

If the issue persists, contact iTunes Support team opening this page (choose your country, then Apple ID, then iTunes & App Store. If your problem is not among the options shown there, tap/click on the option “the topic is not listed” and describe your issue):--> iTunes Store & App Store – Get support for various issues

Regards

Giulio

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Change, add, or remove Apple ID payment methods - Apple Support