tne41

i bought a 2007 Silverado ltz in December 2016. It was a one owner when I bought it. Before I bought it they had the oil pump and a hose and a tps sensor replaced. Since then I've had it in twice for the service stabilitytrak and traction control off messages coming up on my dash. Had it scanned and it came up with a cam shaft sensor and tps sensor bad so I replaced them. Didn't help. The dealership sent it to the other dealership that did the work originally and they refused to do the work since I replaced those two sensors. So the place I bought from said they fixed a couple wires and it was fixed. Needless to say it didn't fix it so now I have to take it in a third time since having it only 5 months. When hooked up to a trailer and using the haul button it's always on. When it's on it shifts so hard when taking off it's like it's going to give you whiplash. Any ideas on what it could be? Because it doesn't seem like the dealer is going to be able/or willing to make this right.