Suspension Noise problems of the 2015 GMC Sierra 1500

I began to hear what sounded like loose rear suspension components about a year into owning the truck. I took it in for service and was advised that per the gm service bulletin, they re-torque the leaf spring bolts. It was fine for a couple of months, then the noise began again. It's now been to the dealer 4 times with 11 days out of service. The response continues to be, they've re-torqued the bolts to gm specs and nothing else they can do. It's very clear by the noise that can be heard, both while moving forward and backing in, something is not within specs. The truck is under warranty and I am a couple of months over on lemon law arbitration. Gm is doing nothing to address what could easily be a safety issue and I'm concerned that the bolts continually need to be re-torqued. I've taken to online forum searches to find that this is a common problem with a similar tap dance done by gm. It's shameful that consumers are buying a $40k to $70k truck and having these issues with no solutions being provided through the truck warranty. And when the warranty runs out, how expensive will this be? not to forget, dangerous. I am concerned that one day, the rear-end is going to come out from under my truck and hopefully it's not while on the highway with my daughter in the truck. My truck is used for my daily commute to and from work. It's well maintained, not abused and has under 20k miles. I've turned to bbb for help and was offered 2 years of oil changes by gm. Oil changes don't fix the problem!.