Renault — deal cancel/delay due to exchange value

We have booked kwid on 12th dec from nanavati Renault, varachha, surat. We had accept exchange deal which they have suggested me. But now they are telling me that further party denied to buy your car with that price..and now they wants to bargain..but I told to Mr. Ashvin that is your fault you have checked my car twice and then you offered that we have accepted..I am getting better exchange value for buying Hyundai santro..but instead I decided to buy kwid. Sales person still saying that he is trying but he is literally delaying or more bargaining.. now I want to returned my booking amount without any deduction.