I thought Google had an automatic "flood" system in place to verify payments and issue refunds based on payment errors? A similar thing happen to me a while back. My niece wanted a new game that had just been released and (with me supervising her) she tried to purchase it off the Google Play Store. She did the same thing this kid did with the purchase failing and her repeatedly clicking trying to buy it over and over. She stopped quite quickly because I obviously intervened.
Checked my account that night and about four payments (each of the game's cost) left my account. The following day Google had refunded me three of them and just charged me for the one successful purchase of the actual game. So ever since then I assumed Google had an automatic failed payment "flood" control.
So does this system not apply to in-app purchases or something?
...The kid was lying.