How do I cancel an in app purchase or get refunded?

I set up my iPhone to be able to confirm purchases with my fingerprint. I downloaded an App and was browsing around trying to see if I liked it or if I needed to keep searching for one I liked better. In doing so I accidentally made a purchase that I couldn’t cancel and immediately went through due to my thumb resting on the home button. I contacted the app to get refunded but they notified me that the App Store and Apple handle all purchases. I went and found my purchase history in my settings and tried to report a problem on the specific purchase. It give you options to choose regarding your problem and I selected the one involving an accidental purchase by when I submit it it says it failed everytime. I just want my money back. Why have an option to report a problem if it doesn’t even let me report the problem?