How can I cancel an automatic withdrawal and payment for a service I didn’t know I had and don’t use

See instructions in How to cancel a subscription from Apple - Apple Support

If that doesn't help, be aware that this is primarily a user-to-user support forum; other Apple users like you. We don't have access to information about charges to your account. See each of the steps in the following instructions. They include information on contacting Apple Support if the other steps don't help: If you see 'apple.com/bill' on your billing statement - Apple Support

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