Seat Broken problems of the 2003 Chevrolet Trailblazer

Driver's side seat was broken and repaired by dealer at the time I purchased it on 22 Dec 2012. Seat unexpectedly broke again while driving on IL toll way. Nearly lost control. I am not a heavy person - 170 lbs. , and was not on very bumpy road.

Driver side seat detached from seat frame recently. I turned towards the back of my chevy Trailblazer ext to talk to my kids and the right side of the drivers seat broke from the seat frame. Upon inspection, there's a flimsy piece of metal holding the seat to the seat frame. When I brought it in to the service dealer, he said the whole seat needs to be replaced at a cost of over $800. He said I can call gm to report the issue and that they may offer me a deal to split the cost since the vehicle is out of warranty. I believe this is a manufacturer's defect because it has never happened before in any car that I've owned in the past. Waiting resolution to my complaint from gm, but this is condition may lead to future accidents!!.