Fuel Injector problems of the 2001 Chevrolet 2500

After going to 2 dealerships with complaints of my truck "dying"; which the first computer read-out said "erratic fuel pressure" and the second one saying "large fuel leak detected" my truck finally broke down on me. The mechanic who worked on my truck was an employ of a Chevrolet dealership and was supposed to have been certified on diesels (per their website) did not know what he was doing without a manual, replaced a fuel injector which I was told after the work was completed that it would not be covered under my 5yr/100,000 mile warranty that my warranty book says it is covered. It took him longer than normal since he wasn't certified and had never worked on one before and the warranty should have covered it.