If the Vehicle was Optimum certified then you should have 30 days or 2500Km to make your exchange.
http://www.gmoptimum.com/en/advantage/exchange-privilege
You must exchande an Optimum vehicle for another Optimum vehicle.
If you want to exchange for a new vehicle or a non-optimum used vehicle then you are starting from a fresh trade apraisal.
If the vehicle you bought wasn't certified through GM Canada's Optimum program for some reason then you are starting from a fresh trade apraisal.
If you don't have anything in writing that says that the vehicle you bought is indeed part of the Optimum program then there is every chance that the dealer misled you at the time of sale, not every used vehicle that an Optimum dealer sells has to be sold in the Optimum program(with associated fees paid to GM), used cars can still be sold as 'buyer beware' used cars but it is the resposibility of the dealer to clearly comunicate that difference at the time of sale.
Thanks for this info. I was not aware that is was only for exchange for another used vehicle and not for a new one. My dealer did end up bending over to help me out. I am very impressed. They are even going to replace and paint my rear bumper that has a deep scratch on it. How many dealer are going to do that after a sale. They even gave me a demo to drive for 2 days and will give me another one on Monday when I have to bring it back for the bumper.
Thanks for all the replies.
A call to GM Canada's customer service line should be able to help you shine some light on what's going on.