How to contact the apple store?

I bought a app and the app developer isn't responding to my request to restore the version I paid for, how do I contact the App Store ad hopefully have them contact the company?

The product is mctube

I bought the perversion for 2 bucks but they pulled the link for the pro version from the App Store and now I can only use the free version to get the pro version but its not working and this company has nothing but a Facebook page smh