i am 20 years old and just purchased a used vehicle off of a car lot i have had nothing but problems since then! when i went in to buy this vehicle they wanted my car as a trade in but werent able to do that because i still owed a little on it but they gave me the new/used vehicle anyway.they gave me $600 toward my old vehicle for payments towards it.now they called me yesterday december 11th and asked me if i traded my old car in! i said no i didnt they asked me to come to the car lot and told me that somebody said on the paperwork i made more money from my job than i actually did and that my old car was traded in.now they have offered me $200 off of my new/used vehicle and they also told me the finance company stopped payment on my new/used vehicle and the car lot wants my old vehicle now as a trade in.but on my contract it states 0 down and 0 trade.so i feel that someone has altered my contract behind closed doors. i purchased this vehicle on december 4th.is this legal? please help me!