how do i cancel a crdit card charge i dont approve of? got an apple receit for somtjing i did not purchase

Has your credit card been charged? Contact the card issuer to depute a charge.

Are you sure the message is legitimate? Does it contain a link for you to sign in somewhere? It may be a scam.

Apple will always address you by your name or the name they have on file for you and the e-mail will be from @apple.com.

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

Identifying legitimate emails from the iTunes Store

Send the e-mail to Apple as an attachment to a new e-mail before deleting it.

reportphishing@apple.com

You are sure that it’s a genuine email from Apple and not a phishing attempt trying to get your account and payment details ?

Phishing and similar emails : Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

Genuine iTunes emails : Identifying legitimate emails from the iTunes Store - Apple Support

Viewing an account's purchase history : See your purchase history in the iTunes Store - Apple Support

If it's a genuine email and it shows on your account's purchase history, and if nobody else has access to your account and did it, contact iTunes Support : https://support.apple.com/contact . And change your account's password http://appleid.apple.com - after changing it : What to do after you change your Apple ID email address or password - Apple Support.

If it is a phishing email you could forward it to Apple : reportphishing@apple.com , and then delete it.