Supposed to repair a broken sliding door

My husband & I purchased a Certified Toyota Sienna (09) from Signature Toyota on 5/29/12. Later that day we found out the driver side sliding door did not close. When we took it in to our local dealership in Indiana it was revealed that the door had been broken, worked on, not fixed, and sold to us with Signature Toyota's full knowledge that the door was still broken. They did not tell us it was broken, did not report the repairs on the Carfax report, and are currently refusing to pay for the new parts necessary to fix the sliding door. They are a shady business - selling a car as a Certified Toyota when it clearly did not meet Toyota's criteria for being called "Certified." Then admitting that they sold it to us defected, but refusing to pay for it. They give "used car salesman" the reputation one expects of slimy, underhanded businessmen.