POOR POOR After sales service

I am totally disgusted with this Kia branch. Bought a second hand car from them end of last year and in the interim the car has developed engine problems. I was assured by the salesman at the time that there was a 4 month after sales cover regarding such issues. I have been struggling since the end of March to get the problem fixed and sadly have yet to see joy. They never phone me back when I have tried to speak with the manager(Micky) as he's always unavailable, his assistant also doesn't bother to call back, I have taken the car in numerous times now and get brushed off with promises. Last Friday after collecting my car for a seat repair they did I was told that they could not find any problem with the motor. I never even travelled 5km when the problem started again so I immediately called them saying I wanted to bring the car back. Booked the car in for today but once again when I took the car in no arrangements had been made as promised. The manager also had the gall to say that they couldn't keep on repairing my car indefinitely!!! THEY HAVE YET TO FIX THE PROBLEM. Needless to say I was sent on my way again with promises. Also waiting over 3 weeks for my spare key