I agree that you should be able to send a complaint on the AT because then the teacher can go in and make the ultimate decision. I am not sure if the punishment should look the same, if the AT only receives 20 galleons a week- it should be much more knowing that they grade tons and make ultimate decisions. I could see them loosing house points though as they get them when they do their own assignments. And give the wrong grade is a sign of poor faith.

It would mainly before larger offenses. Such as swearing on the site, bullying, fights/arguments, Giving someone a Troll Grade because you think its funny when they had a perfectly good assignment. If you continue to do something when people say stop, if there is any form of foul play, encouraging others to behave inappropriately on the site, Cheating on an assignment, accusing others of doing something without evidence, etc. I find it would be more effective than banning someone off the sight. They will have an opportunity to correct themselves this way and learn from their mistakes.