Send the complaints to whom exactly?

Whoever it is, go ahead. Go right ahead.

They're banned because people use them to evade bans, people steal other peoples leaked accounts online. You might think some site is being all nicey nice and giving you free minecraft with a login and password. But they're not, those accounts have been stolen from other users and made public through illegal actions.

But no no, kids like you want to not give any money to the developers, kids like you want to steal from others just so you can have a good time and not care about the real owners feelings.