If you feel that you were charged incorrectly, you will need to contact Apple iTunes and have them credit your account. We do not handle the accounting of personal accounts, that is all done through Apple.
For information on the iTunes Store and In-App Purchases see: http://support.apple.com/kb/ht4009
To prevent accidental purchases in the future, you can restrict in-app purchases on the device by setting up Restrictions.
For information on parental controls and Understanding Restrictions see: http://support.apple.com/kb/HT4213