Why am I being denied a refund for a purchase that was not me by me

I have a 12 year old autistic son who needs to have an electronic in the car during car rides. I had no idea that he has never made a purchase through this game and the most recent one was over $10 and I am being told I cannot get a refund because the security is so good that you need a fingerprint scan even though I explained that my son's fingerprint is registered in my phone along with my fiance's and my own but I never need any purchases not only that I got a $39 overdraft fee for every $2.99 that my son unknowingly used to buy gold the most recent purchases over $10