You do not say where you see this purchase. If it is an e-mail are you sure it is real and not an attempt to steal your private information ('phishing') (very common)?
Phishing & Other Suspicious Emails - https://www.apple.com/legal/more-resources/phishing/
Identifying legitimate emails from the iTunes Store - http://support.apple.com/kb/HT2075 (the previous link is more specific)
Forward attempts to: reportphishing@apple.com