Overcharged

Go through the steps in here and if none of them are applicable, contact Apple as instructed at the end of the article.

If you see "apple.com/bill" or an unfamiliar charge on your statement - Apple Support

if you just got some mail saying you were charged then read

Identify legitimate emails from the App Store or iTunes Store - Apple Support

Phishing & Other Suspicious Emails

https://en.wikipedia.org/wiki/Phishing

if you were really charged

Request a refund for apps or content that you bought from Apple - Apple Support