HT201359 Credit card charged when using credit balance?

Question

If I had a credit balance on my itunes account, then why did my credit card get charged?

Answer 1

Assuming you were not buying a gift for someone else - gifts cannot be purchased using a credit balance - another user in the forums posted this as the reply from the iTunes Store when this issue was brought up. Perhaps it will help you. Regards. 
I'm sorry you weren't able to make a purchase using your store credit. To purchase items on the iTunes Store with your store credit, your account information in your user profile needs to be corrected. I'll walk you through this process to get you back up and running in no time. 
1) Visit the My Apple ID website at:  http://appleid.apple.com 
2) If the site is not displayed in your preferred language, click the Change Language link in the upper-right corner, type the name of your language in the field that appears, then click the Save button. 
3) Click the "Manage your account" link. 
4) Type your iTunes Store account name (which is your Apple ID) in the Apple ID field, type your password in the password field, then click the Sign In button. 
5) Click "Addresses" in the column on the left. If you have multiple shipping addresses, remove any out-of-date or duplicate addresses by clicking Delete. Also, make sure the state or province field is filled out correctly for each address. To edit an address, click Edit. Edit all of your shipping addresses and make sure the appropriate state is selected in the State drop-down menus. 
6) Now click "Phone Numbers" on the left. The area codes should be in the area code fields and the phone numbers should be in the phone number fields. If an area code is missing, or if it is in a phone number field, your account information may not save properly. 
7) Make any other necessary corrections, then click the Save Changes button. 
8) Click Log out in the upper-right corner.  When you make your next purchase on the iTunes Store, you will be asked to review your billing information. At this point, you can change your information or simply click Done at the bottom of the screen to proceed. Once you click Done, you should be able to purchase on the iTunes Store using your store credit.