How to cancel a pending purchase
I can’t download or update any app because I can’t update my billing information because I have a pending purchase for something I did not buy. How do I cancel it?
Purchases are considered final but you could try the 'report a problem' page to contact iTunes Support and see if they will cancel it as a one-off : http://reportaproblem.apple.com
Or you can try contacting iTunes Support via : http://www.apple.com/support/itunes/ww