GM abused their powers to mute players?

I was on 820 trying to sell my reflecting mist, I was on capslock and i posted twice. Then i found out i was muted by a GM for 4 hours? 4 hours? Let alone, there was no warnings or anything... he/she just simply muted me. What sort of power abuser do that? GGG should train their GM to be nicer players first!!!