HT4009: iTunes Store: About In-App PurchasesLearn about iTunes Store: About In-App Purchases
All purchases are final, but you may be lucky if you contact iTunes Support.
It's a bit late now, but before letting your son use your device, you should've done this:
Settings > General > Restrictions > Enable Restrictions > Enter a PIN
Settings > General > Restrictions > In-App Purchases > OFF
Settings > General > Restrictions > Require Password > Immediately
This is all in the User Guide, of course.
i purchased only one app which was only 69 pence so i had to put my card details, very next day he played on ipad just 30 mins and after some hours i recieved the mail reciept.. do you know how i can contact to apple via email or fill refund form, its not too late,,