I also read the OP that it was the TV salesman that said the truck had a tow package. We bought a car that the salesman assured us had certain features we wanted (technology package). We asked more than once. When we took the vehicle home and I was looking through the manual to figure out how to use them I quickly discovered the car didnt have the package. We took the car back to the dealer, spoke with the manager who agreed it didn't have the features and gave us $1000 cash to keep the car and as an apology for the salesman misrepresenting the car. I still wasn't happy but I accepted the $1000 and went to another dealer when it was time to trade it in.
I know it's not the same as this couple but it is worth a shot for them to go back to whichever dealership misrepresented the sale. Yes, buyers should educated themselves but the sellers do have some responsibility for what they say. The salesperson offered his opinion knowing that the buyers were basing their decision on his answer. If he doesn't want to be responsible for what he says than he shouldn't have said anything.