If you received an email about a purchase that you did not make, it might be a phishing scam. Don't click on any links in the email, or call any phone numbers. Check if the purchase is real.
See your purchase history in the iTunes Store on a Mac or PC
If there is a purchase that you did not make, file for a refund and change your passwords.
iTunes Store - Contact Us - Apple Support
If there is no such purchase in iTunes, contact your credit card bank. It’s not an Apple issue to resolve.