Gas Recirculation Valve (egr Valve) problems of the 2006 Chevrolet Silverado 2500

I purchased 2006 silverado new and after the 1st year noticed rusting. Just before it came off warranty (2009) the coolant line from the radiator and the brake rotors (front and rear) had rusted through. Have since replaced the rotors again and now my brake line burst open as I was driving home. Entire undercarriage is rusted (frame is peeling up in layers), there is rust coming through the bumpers, on the wheels, in the bed, inside the driver's door - basically everywhere I look (I filed a complaint with Chevrolet in 2010 about the excessive rusting and was told, after inspection by local dealer, that there was "no abnormal rusting found"). I baby this truck (it only has 26,000 miles and is not driven on the roads when they are salted) and keep it very clean. I am afraid for my safety as I do not know what is going to fail next. Today I spoke with Chevrolet again about the brake lines, again inspected at the local dealer, and was told that it was "normal wear and tear" and caused by environmental conditions. In addition, I was told that the rotors and calipers are rusted through and must be replaced. How is it possible to conclude that the corrosion is due solely to environmental factors and not at all due to material choice and lack of appropriate coating? I am only asking that they cover the replacement of the brake lines and they do not feel obligated to do so. They do not believe it is poor design or subpar materials. (neither of my other two vehicles, 1993 Toyota pickup and 2004 Volvo, show rusting of the undercarriage to the same degree as the silverado and the brake lines of both other vehicles are completely intact. All three vehicles have been subjected to the same environmental conditions. ).