I have a charge from iTunes I did not buy

First check if the purchase was made from your own Apple ID and whether you may be able to identify the charge. Look into your purchase history and subscription management. Visit Report a Problem to see if you can resolve the issue yourself, otherwise contact iTunes Store Support.

If you received an email claiming to be from Apple Computer with charges you do not recognize or with requests to provide or change personal information DO NOT click on any links or respond to it.

Avoid phishing emails, fake ‘virus‘ alerts, phony support calls, and other scams

https://support.apple.com/en-us/ht204759