I had to report someone for abusing their mentor privileges and kicking several people. GM Elrindonar was very quick to respond and he did so in a professional but personable manner. My experience in this situation was so positive that it encouraged me to make my first forum post in over 3 years.
Side note: thanks to him I found out that GMs are required to use "Gm" in their name and thanks to me, he found out that the GM chat had a specific tag [GM] that his messages are displayed in. It was win/win for both of us tonight.