Been ripped off by dealer, What to do?

Last Feb I bought a beautiful 1989 560SEC from Glauser Mercedes in Sarasota, FL. Car had 59k on it and is/was in fantastic shape. Car was carfaxed, gone over with a fine-toothed comb etc. according to the sales manager & saleman. In looking for a some info. I ran across DUG's free carfax today. Ran my car and BAM! 2 counts of speedometer rollback, front end collision damage, Not only that it had a "NOT ACTUAL MILEAGE TITLE" issued in 8/98. What can/should I do. If discrepency was small, I would sluff it off because I love the car and under my extended warranty,$6000+ of work has been done, she is tip top. Problem is a 63K mile discrepency! The car now has over 140k, not the 71 indicating. They are currently "looking into it". Regards, Nick