30 day ban for buying tokens to sell?

My buddy that has been playing for many years just got banned last night while he was at work. The ban says he abused the wow token system buy buying too many to make gold in game. He bought 4 last month and 3 this month. Has anyone else had an issue from this ? He tried to appeal but they just replied back saying that the complaint will stand, no appeal ??? Does anyone know anything about a limit on how much money you can spend on blizzard before they ban you for buying something they put in the game ?