Unauthorized In-App Purchases

EXTREMELY upset and disappointed with the service I have received with Apple. I was charged for 40 in app purchases worth $2000 over a 3 week period. None of which I authorized!! The Roblox game is played by my 6yr old and he does have the account password and knows not to purchase anything. Some transactions, worth $158+ were charged multiple times over a span of 3-4 minutes. There was either a glitch in the app or my card was compromised. I wouldn't even have known about it unless my credit card company sent me a text. Regardless, Apple should have honored the dispute and refunded me the money if they had an ounce of respect for me as a customer or my experience with Apple.  EXTREMELY upset and disappointed!!!!!!!!!!! Can someone please assist.