FireBird Frenzee

I went to Wal-Mart to have a tire patched. I accidentally drove over a nail in front of my new Dominion home (That is another story though.) and I was told that they were the only place nearby that could do a quick-fix chemical patch. After all, at $120.00 a piece and this being my 2nd nail this month what other choice do I have? Well, an hour and a half goes by and I am with my wife shopping so we decide to drop by Wal-mart on the way home to see if it was completed yet. When we get there the car is sitting in the center of the parking lot with its flashers on and a woman standing there saying that they were not liable for damages done to the car. It turned out that the rear differential snapped entirely in half! 2 inches of steel! Well, I had it towed and I owed the repair shop nearly $2,000.00 Parts and labor for that and a cracked casing. I was also told that this happens when the car is drag-raced or there is a leak from the casing. No, I would notice a leak I told him. Then he told me that the guy at Wal-Mart most likely threw it into drive while the car was rolling backwards and the head and horsepower would snap it like a twig! What can I do? They say that they are not responsible and I had it towed from where it happened! Please help, I am at my wits end with Wal-Mart!