I've had good and bad experiences with dealerships and maybe the service advisor was having a bad day too. Good customer service isn't what it used to be - if it ever was! Some people bring in stuff they actually broke and try to claim warranty. People try all sorts of things - not saying you did. There is nothing like bringing in a copy of the TSB. I did this with an Envoy that had a cracked exhaust manifold. Initially they told me it wasn't covered, then I brought in the TSB and they covered it but I had to educate the Service Advisor first otherwise I would have had to pay.
Speaking of customer service - I have an 07 GT with the 2 piece spark plugs, took it into a local dealer and asked about changing plugs. The Service advisor just laughed (which really p1ssed me off - so I know how you feel getting 'attitude') and said it would cost $400 if none broke and up to $1200 if they all broke. So I did it myself and reluctantly go back there.

At least they said they would cover your issue under warranty. I've heard that Woodridge is one of the better dealers in Calgary if you are close to them.