Trade in asistance

Once again we buy cars disappoints me with out fail, I traded in my car to them and the car I got had a problem within a month, took the car back and we agreed to start a new deal, in that process I have to use public transport because I traded my car in, now I'm told I don't qualify for trade in assistance because it's not part of this deal how is that possible if I had bought a car that qualified for trade in assistance at first does it mean I would have lost trade in assistance on the new deal because I didn't trade in for this car?