Gradient app. Money charged without permission
Hello, dear Community members!
I‘ve been using AppStore and iTunes for many years, first time there is a problem like this - Gradient app asks for 3 days free trial usage without any other options available. Many people (according to reviews) face it. There is no other choice, so you choose 3 days trial but you are charged 20$ for a month right away. I tried to write to their support- nothing. Tried to get my money back through Apple - my message got an automatic reply that it is not the case. What should I do? Is there some way to stop this scamming? Help please.
iPhone 11 Pro Max, iOS 13