If you filter who can complain, you do not have to deal with those that you do not care about.
SAAS with free tier does it this way:
* To contact support via non-app method you need a PIN. PIN is displayed when you login into your paid account. Don't have a PIN? Can't connect to support.
* To contact support via app method your profile needs to be associated with a paid account. Don't have a paid account? Can't contact support via inapp
