Front Suspension Lower Ball Joint problems of the 2012 Jeep Wrangler

I had already experienced the death wobble in my Jeep prior to today's date, I had everything under the front end tightened and the front track bar replaced, cost, approximately 700 dollars. The track bar was replaced April 30 2015, today may 1 2015 I got on the highway ramp as soon. As I hit 65 and a bump the Jeep began to go into a violent shaking. In order to maintain control I had to grip the steering wheel very tight, white knuckle, and pull off to the side of the highway during morning rush hour. After coming to a complete stop the wobble stopped. I bright to Jeep and the said probably the steering. The called me later and said it was the upper lower ball joints, tie rods, alignment, and steering. 2200 bucks. For a car that's only a few years old no reason something like the ball joints should be that worn or that I should experience a death wobble in the first place. I don't off road, my car is not lifted. Jeep is not willing to pay any of the repair even thought the car is like brand new.