We understand that these things can happen.
In order to process a refund, you will need the email receipt/Google order number associated with the unauthorized purchase.
To find a copy of the receipt search "Google Play" in your Inbox and send a copy of the receipt to firstname.lastname@example.org
Please know that our apps cannot bypass your security/password requirements and that it may be necessary to update your password if unauthorized purchases are being made. If you have further concerns or questions about your password security you should contact Google Play directly.