When I get a service I am having trouble canceling, I call the credit card company and scream fraud (whether it really is or not). I don't play games with billing. I'll ask once for a refund or correction, then after that it means war.
My sister joined a gym in Toronto and was tricked into signing up for a "lifetime membership" (What? Who in their right mind would sign up for something like that. What if you have to move, or fall ill etc.). She had to move out of the area, and they refused to cancel the membership and kept billing. So she just called Visa and got them to stop the payments (and claw back the last 2).
Maybe things are different in Canada, but credit card companies generally will protect you from bad behaviour.