iTunes gift cards and iCloud payment

See: How App Store and iTunes Store purchases are billed. Click here --> https://support.apple.com/HT201359

"Which payment method is charged?

When you buy items or pay for subscriptions, Apple automatically attempts to charge your payment methods in this order:

1. Apple attempts to use your Apple ID balance (where your cards go) to cover the full amount.

2. If you don't have Apple ID balance, you don't have enough to cover the full amount, or an item cannot be paid for with Apple ID balance, Apple attempts to charge your primary payment method. The primary payment method is at the top of the list in Settings on your iPhone. You can control which payment method is at the top of the list.

3. If there's a problem with the primary payment method, or if the primary payment method can't be charged for the full remaining amount, Apple attempts to charge your other payment methods in order from top to bottom. If none of them can be charged, Apple may try again.

Please note that most people posting here do not work for Apple, we're just very unofficial volunteers, users like you, trying to help others. Feedback for Apple will likely get more attention if you send it using:

Click on this link for Apple products feedback links --> http://www.apple.com/feedback/