P.R.
Hi C.,
World of Warcraft is really addictive - I should know, I've played it, and my husband has logged numerous hours on it.
One thing you can do rather than canceling your internet, is to put a block on when he can play through the parental controls. The website with instructions on how to do this is: http://www.worldofwarcraft.com/info/faq/parental-control-...
I'm just thinking that maybe finding a compromise rather than cancelling your internet all together would help from him outright rebelling/etc.
If it's really something that he'd do anything to play - maybe you can increase the allowed play time as he starts to do better in school/around the house.
Hope that helps..