Hi Haroon,
You can sum up the whole mess in the one sentence that you said: "In the end, trusting that they were acting in our best interests, we signed the papers and took the car."
What can I say?!
Often, when there is negative equity in a trade car dealers will raise the selling price of the purchased vehicle, and also raise the trade-in allowance the same amount thereby showing the trade allowance as the same or a little higher than the payoff. Many banks won't allow negative equity on a car loan.
So by raising the selling price and the trade allowance the same amount you are still buying the car for the same price difference,
but it looks better on paper.
Now, I have no way of knowing if this is what your dealer did. I am very suspicious over the fact that they made you take the warranty, rustproofing and so forth.
They legally can't force you to take that stuff, so by giving you some "BS" story about taking that stuff tells me they were being less than honest with you.
If they lied to you on that stuff what else did they lie about?
This stuff happens to people all the time. All you can do now is eventually pay off the car and move forward. Do yourself a favor in the future; If you owe more on a vehicle than what you can get for it don't trade it. Keep it till the end of the loan.
This will save you many headaches in the future. Also, don't allow yourself to be talked into something you don't want. Take a few days to think about it before you make a decision.
Car dealers live by the adage that there is no tomorrow. Everything is "now!" They want you to make a quick, emotional decision. They know that if you take time to think it over you'll probably come to your senses. This is the last thing they want!
All my best....
Tony Iorio