Benchmark auto buyers of long island Mark marbreiter Sold car after bouncing pay of check and received lien release Baldwin New York

 My 2008 cobalt had my name and my grandfather's name on the title. When my grandfather sold the car, Mr mark marbreiter maybe a deal purchase the car and pay the remaining lein amount off. He however sent a check in and the the lein company issued a lien release without waiting for the check to clear. He then re titled and re registered the car and sold it, with a remaining balance of $1644 on it. This car was retitled in 2011. I no longer and the owner of the vehicle so now I have on the hook for the remaining balance. This car reports Un paid evey month since 2011. I don't understand how this is possible or legal. I never signed a title for the car.