Dealership sold me car with wrong mileage- branded title, need help.?

Bought the car in 2007. Trying to sell it now, and realize the title is branded because the Car fax is showing "not actual mileage". I go to the dealership and they give me and Odometer Statement telling me it was the tag agencies fault. I look at the statement and it's from the person before me who sold the car to the dealership. The mileage is off by about 200 from my Odometer Statement. I can't sell the car with out this being fixed. The dealership isn't cooperating to help fill out the paper work with the correct mileage so we can fix it with the tag agency. Can anyone lead me in the right direction? Can I sue the dealership for this? What do I need to do to get this fixed?