App Store account

Hi, I currently have two different accounts, one for my iCloud and one for my App Store. My App Store has recently been compromised and I keep getting emails stating I’ve downloaded multiple apps in different countries on different devices, I’ve changed my passwords but I cannot access my App Store account online to request a refund on a certain app that has been purchased using a subscription. I have cancelled the subscription but would like my money back, could you please give me some info on how this would be possible?

Many thanks.