You can report people through the ingame menu. Not the big forms to fill out, but there's another one on the main page to request GM assistance. It's somewhat hidden underneath the "ask a question" in the In-game Help. Since it was announced during the patch notes that abuse of this system will be severely punished, best thing you can do is try and get them suspended for it. Should they not be willing to oblige your request, i feel the Vote Kick option needs to be removed from the game in its entirety. It's bad enough sometimes already.