Refund

I've recently discovered a bug with the game Roblox when it comes to purchasing the in-game currency. Whenever I would purchase the in-game currency, my bank account would no update with the new amount I have left neither would it show any history of purchasing the in game currency. This happened for 3-4 days straight until yesterday where it has updated the amount of my bank account. I've talked to ROBLOX Support to ask for a refund with the in game currency I have now. They told me to contact apple support if the purchase was made on mobile.