I can’t update my app because of billing issue but there’s no issue

Start reading this support page:--> Subscriptions and Billing – Official Apple Support, and check each of the first 4 sections.

If you cannot find the information you were looking for, please contact iTunes Store Support Team directly, using this link:--> iTunes Store & App Store – Get support for various issues, and choosing: 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.

Regards

Giulio