Hi KimiCHHH,
I’m sorry to hear about the issue!
First thing first, our app is not a game, and it’s free to play, so if your child accidentally added it to your account, don’t worry, there was no payment involved. As I don’t know anything about your Steam account, I can’t verify whether you own any of our titles.
If there was a DLC purchase, then, unfortunately, there isn’t anything we can do, as Steam is in total control over all transactions, and they aren’t exposed to us, developers. Subsequently, we can’t offer a refund for them.
As far as I know, Steam has a no-refund policy on DLC purchases, but you can always raise a support ticket with them and ask. However, they generally don’t buy the “someone else used my credit card” story, so a better explanation of why you don’t like your purchase will be needed, even if it is the truth.
IÂ hope this helps, even though this isn’t the answer you were hoping to get. Please let me know if there’s anything else I can help you with!