Received Receipts for Purchaces Not Mine

They are unlikely to be from Apple, they are more likely to be phishing attempts trying to get your account and payment details.

Phishing and similar emails : Phishing & Other Suspicious Emails

Phishing emails : Identifying fraudulent "phishing" email - Apple Support

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

Viewing your account's purchase history : See your purchase history in the iTunes Store - Apple Support (on an iOS device you can view the last 90 days purchases via http://reportaproblem.apple.com)

If they're genuine emails and they shows on your account's purchase history, and nobody else has access to your account or devices/computers, then 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 they're phishing emails you could forward them to Apple : reportphishing@apple.com , and then delete them.

It is a phishing attempt. Do not respond. Do not divulge any personal or financial information. You can use the address below to forward the suspect email message, as an attachment to Apple.

reportphishing@apple.com

The link below has information to help identify fraudulent emails.

http://support.apple.com/kb/HT4933