Imperial Ford Cape Town - Promise you a car and sell's it to some one else

Imperial Ford Cape Town - Worst service I ever received when trying to buy a car. Late Monday afternoon I get a call my Ford finance has been approved and upon acceptance the car is mine. Next morning just past 7h I let them know I want the car. They told me great they will start on the paperwork. After not haring anything more from them (still waiting for them to phone me as promised), I give them a call just to find out they sold the car to some one else. How do you tell someone I'm busy with your contract and then a few hours later you decide your selling to someone else.