Assuming that you are not the sole individual who believes that this person is abusive, continue to report them, and encourage other players to report as well. When one individual gets enough reports, the GMs will take action. Make sure that the individuals doing the reporting emphasize that they are not the only ones with an issue with this person, and that other players have reported them as well.

Investigating a single report of harassment takes work. The GM has to review the dialog, and make a determination whether abuse was actually occurring, or the offended party was being oversensitive, etc, etc. A GM that makes a wrong call too often in such situations can find themselves out of a job - and rather then take the risk, they err on the side of caution. But when an individual gets a LOT of reports against them, though, the chances that it's just one player with a bruised ego lashing out become much smaller.

Also, if you are a sprout, and a Mentor is repeatedly kicking you without cause, that'd be a good thing to bring up with the GM, as well. They're going to be a lot more attentive if a newer player is being harassed. If you're another Mentor, though, I could see them seeing it as a player-to-player dispute, and would be less likely to intervene.