How can I file an official complaint with apps that charge me after I cancel subscriptions?

I am finding that many apps that I sign up for the trial period and cancel it within the time period, continue billing my account monthly and sometimes even weekly. I have this problem with five different apps in the past 6 months and I getting a complaint to Apple Pay is almost impossible because there is no way to explain the problem to them. If the issue isn’t listed then I have to choose Other and they are reject my request. Anyone else have issues with this problem?

[Re-Titled by Moderator]