Redeeming iTunes gift card

Open iTunes, go to the iTunes Store and on the right side, under Quick Links, click Redeem. You will need to enter your Apple ID, and then you will be taken to a page that looks like this:

You will then enter the Redemption Code or let your iSight camera scan it. When the card has been accepted, the amount of your subsequent purchases will be deducted from the gift card until you reach a zero balance. After that, iTunes will start charging your cc again.

Was the purchase a gift to someone else? If so, that's why your credit card was charged. You can't use a credit balance to purchase gifts.

If the purchase was for yourself, did it actually charge your credit card? Or did it just ask for you to verify your billing information? The latter, if that's what it asked, is a normal security precaution and not actually a notice that your card will be charged.

Regards.

By default payments will go to your iTunes gift cards. You have to specify that you want to pay by credit card or not have enough money in your account to pay by credit card.

You cannot specify that you want a charge to go to a credit card if you have a credit balance. That balance will be charged automatically until it runs out, unless again the purchase is a gift.

Regards.

I called Apple support. After making a purchase it looks like your credit card was charged until your account is refreshed by signing out & back in. Once you sign back in your iTunes card balance should update.