You're right, one should know and understand what he gets into. That part is your responsibility.
But when you enter a contract both/all parties should fulfil their end of the contract and it appears that GM does not take this too seriously. And that should change. They have half a million customers, bet you'll find a number of good lawyers among them. (and quite a few baseball players)
As long as you stand alone, they will screw you front, back and sideways, top and bottom.
Unite and the odds change in our favour.