Lund Cadillac Legends Cadillac Frame Damage not reported- car unsafe Phoenix, Arizona

Purchased a 2007 Cadillac CTS, Sept. 21, 2009, as therortic 2nd owner. Went to trade car in with a different dealer on January 17, 2011, was declined to trade the car in due to frame damage- value of car was stated to be at salvage price of 10K.
Contacted Lund Cadillac currently 4 times with no resolution to make this right-
After pulling a GM history report on this vehicle- found the following: vehicle was put into service at 15 miles as a loaner- never reported to DOL of AZ- vehicle never reported as required by law as a loaner (hence 1st owner).  Also found from the report that 200 miles prior to us purchasing this vehicle the front hub as well as the complete rear differential assembly was replaced, not discolosed.
Vehicle at some point in time had been in a major accident that was never reported- bumper has been cut from supports and cut off from the frame and welded back on- no protection for a rear end impact.
The integrity of the safety features of this vehichle has been compromised.
Also, Lund Cadillac reported our purchase days after the actual date.
Their attorney has contacted us twice and each time denied having any knowledge of the vehicle's condition, although they purchased the vehicle from the previous owner, whom serviced the vehicle at their dealership on a regular basis. Their attorney also stated that Lund Cadillac would welcome the idea of us bringing the vehicle in as use it as a trade in- only to recirculate a vehicle that is not safe to drive, and have us spend more
money. Currently we have reported this to the Attorney Generals Office, 3 on your side and the BBB. Waiting for results. This past week alone, we have made 3 phone calls to their attorney with no return calls.
All we want is a safe car to drive.