Try to find out if the selling dealer is a member of the U.C.D.A. (Used Car Dealers Association)
UCDA Home Page or even better T.A.D.A (Toronto Automobile Dealers Association)
Trillium Automobile Dealers Association - Welcome to TADA
Look for info on what protection you may have if the dealer is a member of one of these associations. Do your homework prior to making demands at the dealer but also call the Associations first.
Good luck.