Engen Garage Hibberdene refuses to fix my car

It was the 8th of May (Thursday) at 7:25am where I went to the Engen garage in Hibberdene to put fuel. I was assisted by a petrol attended called Siyanda Sengane. I asked him to please check my water and oil he opened the bonnet confirmed that I needed a pinte of oil so I ended up paying R265.50 for fuel and oil. So I drove off as I was driving in Port Shepstone I noticed my car had smoke coming out of the engine eventually I parked to check the petrol attended (Siyanda) did not put back the radiator cap so I had to buy another one at Auto Zone in Port Shepstone for R130.00. Didn't use the car the following day because it was using a lot of water and was scared something had happened. So i found out that he was working Saturday night so I went to him at 18:38 and told him what had happened and he admitted that He did not remember putting the cap back. Monday morning drove the car to take it to the mechanic at Renault but the car didn't arrived had to get it towed to confirm at the mechanic that the car over heated and the head gasket had exploded. Been talking to the manager Zakhele Gumede but he's always giving me excuses and runaround till today. Please assist I really need my car fixed I do not have the R22 000 for an engine