Request a refund

I have 2 devices, logged in with 2 different account. My kid play game on them and purchased some stuff that I did not know and allow so I made request for refund on these 2 account. But the request for refund on 1 of my account was rejected, 1 succeeded. The rejected request costs much more money, what should I do now? How can I contact customer service for help? I already told them that my other account request was accepted, and I can provide evidence but did know how in the ticket.