Transfer balance back to iTunes card

No, that is not possible, see -> Check your Apple Account balance

Check your Apple Account balance – Apple Support (UK)

Spend any balance remaining on your Apple Account balance.

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If you have an Apple Account balance that you can’t use

You can't redeem or return Apple Gift Cards, App Store & iTunes Gift Cards or unused Apple ID balance for cash, except as required by law. If your jurisdiction allows the refund of redeemed gift balances, you can contact Apple Support to request a refund. 

When you contact Apple, include the following information:

•               Your Apple ID.

•               The refund amount.

•               Your current delivery address.