I was charged even though I cancelled the subscription
I used an app just for a few minutes to check whether I need it or not.
There was a 3 days of free trial version after which you pay.
After realizing I wouldn't need the app I cancelled the subscription plan and all went well unless I received a charge for that app in 3 days. I double-checked if really had cancelled the subscription, and I had.
So what's problem? How can I get the money back and be sure I won't be charged again?
iPhone 11, iOS 13