Apple refund

Go here - View, change, or cancel your subscriptions - Apple Support

and here - Subscriptions and Billing - Official Apple Support

contact the app developer too.

If you paid with Apple Pay

If you see a transaction you do not recognize or have an issue with a transaction open Wallet>tap on the card used>tap on the transaction (photo 1)>tap on the amount (photo 2)>look for a report an issue link. (photo 3)

photo 1 - select the transaction

photo 2 - click the amount

photo 3 - click the link

Did you already go here - iTunes - Official Apple Support

and here - https://support.apple.com/en-us/HT204084

Go here and see if there is a live chat or phone number available - https://getsupport.apple.com/

If they have not rejected it then it is being determined probably. You may just have to wait longer.