Appalling Webuycars.co.za The Dome Experience

I have recently bought a car on Auction from We Buy Cars at the dome. I used the car for two weeks and decided to sell it and look for something smaller. On the 14th of April I went to a Branch to sell the car, Mr Klerk took the keys and went out to test the car. So, when he came back he gave me the key and made an offer, of which I was still thinking about and took the keys and continued to look for the smaller car. To my surprise, as I was about to leave the Branch at around 17:40, the car had stopped working and Mr Klerk was the last person to be in the vehicle. Also, the car has been running all along but after he took it for a test the car never started again. What is worse is that, I tried to contact him since the 14th and now to get an update with the car but he didn't response to numerous messages. I was told by his other colleague that they will get the mechanic to check the car. I am truly not happy about this and will not be doing business with Webuycars no more.