Ball Joint problems of the 1998 Chevrolet Blazer

Moving at approximately 15 mph in a condiminium plan, I rounded a curve when the right front side of my vehicle dropped down and my vehicle swerved right onto the grass hillside beside the road. When aaa arrived, it looked like the wheel had fallen off. After having it towed to the nearest dealer, they informed me that the tie rod had pulled out of the ball joint which holds the wheel to the axle. The service manager then informed me that they would not fix it under warranty because it was his impression that something had been hit because their was grass and dirt up under the front right bumper and wheel well. I explained to him that the grass and dirt was from when the vehicle slammed into the grass hillside after the wheel fell off but it did not change his opinion. I decided to pay $300 to tow my vehicle back to the dealer I leased it from. They would not fix it under warranty either citing the original service man's report. After several letters and calls to Chevrolet's customer service, they finally responded to me and said there were no grounds for fixing the problem under warranty. The damage to the vehicle ended up being $1200. 00 to fix the ball joint and tie rod. Not to mention another $400 for body work. On top of this, my dealer claimed that when the wheel fell off, the entire frame was bent. How could a sport utility vehicle traveling 15 mph get its frame bent from the tie rod braking? on top of that, it took my dealer, 5 weeks to fix the problem. It cost me $750 out of my own pocket to pay for a rental car. I didnt' turn it into my insurance because they informed me they would have to list it as an 'at fault accident' since the dealer would not fix the problem under warranty. So basically, a manufacturer's problem cost me $2250. What bothers me, is that the whole process was determined by the first moron service guy at the initial dealer who reported that it was his opinion something was struck. Chevrolet would not send a service mgr.