I agree with the other post Jeff, I think you should take it to a different dealer. See what they have to say. If you want, remove the hitch and wiring from the back for now, take that out of the equation. If Your bumper to bumper warranty is still in effect, it should cover the rear trailing arms no question. As said Prior, unless they can prove you were Towing overweight, then they should replace it under warranty. As also said Prior, go to kia direct if you need to because this is a bunch of baloney. Good luck