Engine Exhaust System problems of the 2003 GMC Sierra

I wrote gm on October 26, 2013 about my 2003 GMC Sierra duramax diesel 6. 6l 6l that just recently started billowing bluish black smoke constantly from the exhaust and costing an exorbitant amount of money in gas. I took it to the dealer (quality by dilorenzo in albuquerque, new mexico) and they informed me that there was a bulletin issued in October 2006 for leaking fuel injectors. They diagnosed my truck with the exact fuel injector problem. The truck only has 83,502 miles on it and I've been informed that the next time I take it for an emissions test (a requirement in new mexico) it will fail. I finally saved up enough money to go an outside repair shop on July 15, 2014 to get my fuel injectors replaced and the total came to $4763. 78. I found out that there were two stripped bolts indicating that the fuel injectors were previously repaired (additional cost of$12 each to replace the 8 bolts). I called the original owner and he told me that the injectors were repaired under the original bulletin (04039) in June 2005 at tillery motors in belen nm. Therefore, the fuel injectors were never really repaired properly in the first place. I have spoke to another women (kathy) at the gm customer service center. She is again elevating this issue to a specialist under gm id #71-1331886730 for reimbursement of the total cost (standard 24-48 hour call back).