Hi. My nick in Minecraft is jrmpinto. I was banned for grief, but I didn't grief anything. Somebody has used my account and griefed something! I don't know who was, and what he/she griefed!!
You wont get much help the mods on the server are very cautious before they ban and if they said you griefed they know because they used the big brother plugin on a griefed block and your name appeared i highly doubt that they made a mistake