Frame And Members problems of the 1997 Ford Mustang

At complete stop - hit from behind - mechanic doing repairs stated there are no safety brackets under the car - the car & doors buckled on impact. Do convertibles have to have extra safety brackets installed under the frame?( dot number: ).

Conv frame is cutting top(can be easily seen), dealer says is vandalism and will not replace, top shop says if replace frame will do same thing, dealer will not repair frame.

My main concern is with the welding on the rear of the car. I have had the car looked at by more than one independent maintenance professional who has stated that the original defect, the improper welding of the brackets on to the unibody at the factory is a non-repairable defect. Originally, the dealership found the defect and represented to me that the body shop would be able to fix the defect. At that time, I was told the rear tires were pointing to the right. Now I am being told by everyone other than the dealership that they are "toed to the left - no adjustments can be made". At the time the dealership put the car in the body shop for "re-welding" it had only 20628 miles on it, and the tires were completely ruined. The dealership refused to make any allowances for new tires. At that time, the car would fishtail and swerve on right turns, even from a dead stop. I informed the dealership that now the car does the same thing on left turns. I have had them look at the vehicle three times in the last month, and their consistent position is that there is nothing wrong with the vehicle. The manufacturer's response was that I needed to go through the dealership. I purchased the car new and paid for an extended warranty which had not expired at the time I brought this back to the attention of the dealership and the manufacturer. At this time, however, the warranty has expired. I do not feel that matters, however, as the defect here is a manufacturing defect that according to the information which I have, is non-repairable. I have provided the dealership with the computer printouts which I have from other technicians explaining the problem, but, as I said, their consistent position is that there is nothing wrong with my car. And that is pretty much the extent of their explanation. I will continue to pursue my position with the manufacturer, hopefully with better success.