If you or another person (such as a child or friend) has made an accidental monetary purchase on an iOS device, please contact Apple Customer Support for a refund. They can be reached at https://support.apple.com/contact. Apple does not grant us access to any billing or credit card information, so we are unable to provide a refund directly.
To prevent an accidental purchase, if you go to "Settings" > "General" > "Restrictions" on your iOS device, you'll be able to enter a pin number that prevents any unauthorized real-money purchases inside iOS applications.