Underhood Wiring problems of the 2007 Chevrolet Silverado 3500

We purchased a 2007 Chevrolet 1 ton new in August of 2007. On January 23, 2008 my employee was delivering traffic control. The engine was running as he was doing his paper work. He noticed smoke from under the engine compartment. He opened the hood and observed flames and smoke. He used the fire extinguisher, that is part of our on board safety equipment, and proceeded to knock down the fire. We had it towed to watson Chevrolet, where it was purchased, and there it remains to this day. The wiring harness has been ordered more than once and more than once the manufacturer has sent the wrong one. I am reporting this after reading about the fires in the full size SUV's. My understanding is that the engine and drive train are similar in these vehicles and in my 1 ton truck.