Did you sign a piece of paper promising to buy it for the next year? They do this even after 3 or 5 or 11 years of service after all, so even in the unlikely event there was a proper contract, your complaint is sort of moot.
Are you going to claim that it's a verbal contract? Those are rather narrowly defined. Telling your friend "Oh yeh, I'd buy one of those when you get one in!" isn't a verbal contract. At minimum, there's no mutuality going on here. They suffer no detriment from 1 in 10 zillion subscribers forcing a cancellation they made impossible in the first place. Verbal contracts should require, at least, that someone met you face to face and heard/saw you assent.
There's a strange cultural phenomenon going on in the modern world, where people believe that contract norms/laws govern things that they absolutely do not.
But a company suing you to get monthly payments for future monthly services raises so many red flags that I can't imagine anybody even accepting getting involved with it.
Edit: Has anyone used this technique and got into legal troubles?