Carhop Blaine 8 days and the car is broke Blaine Minnesota

I bought a car on July 8th from Carhop in Blaine, MN. On July 16th, I was driving to work and the car overheats. I look under the hood and there is a frayed broken belt hanging there. It's the serpentine belt. Less than 200 miles driven and it's not covered under warranty because it's considered normal wear and tear.  Showed a mechanic the belt and he stated the car should have never been driven off the lot. Carhop wont pay for my towing. I want them to exchange a vehicle but since it's longer than 72 hours they wont do anything. I feel like such a sucker!