Opel 2014 Corsa OPC engin not fully repaired

On the 28th of December 2015, with less than 55k on the clock the car broke down as I was driving from Mafikeng to Johannesburg. The car was unfortunately towed to Tommy Martin- Roodeport which was the nearest GM dealership. After that ordeal I had to contact the dealership numerous times to get an update on the vehicle as they were progressing very slow with little information which was relayed to me. I was later told that the cooling system had failed and they will have to fit a new engine. I was promised that my car will be completed on the 29th of January 2016. In this period I had contacted the Opel customer call centre as I was not pleased with the service received from the dealership.Ultimately they failed to meet the deadline of the 29th of Jan and I only received my car on Thursday, the 18th of Feb. I drove the car for 2days when I noticed smoke coming out from the bonnet at which I stopped and called to get the car towed again. I received the car a week later on Friday, the 26th of Feb. I have now been driving the car for six days and the engine is making a rattling sound, and the car consumes far more petrol. Opel may you please get my car fixed.