Olgar are not to be trusted

I have had bad experience with this garage. I bought polo vivo trendline 2015 from them only to find that when i tried to trade in the car it was a polo vivo concept line. My contract and every paper states the car is concept when its not. I contacted them and they admitted to their mistake and said they willing to correct it said they will open a new account and correct the papers of the car, the settlement will drop and the instalment also. They told me to put that in writing and when i did. They said its only the car discription that was mistaken not the amounts which is not true. Im paying R4230 instalment and when i try to trade the car in they say its settlement is too high for this car. Olgar take advantage of people who have less knowledge about cars. The manager now ignores my calls and do not want to talk to me. I have all the emails they sent me but never stick to their promise to resolve it till today