Kia Weltevreden park did not change the oil on my car

I am so disappointed with Kia Weltevreden. On Saturday I felt like the is a bit of disturbing sound on my engine, felt like tappet noise (minimal). I thought that maybe is because it was due for service. I stopped using it, until I took it in for service yesterday, worst decision of my life, the car still has the sound, the performance did not improve in anyway. The master technician there told me that since the car is on 62 000 km is normal to start making sounds as it is not new. I believe that the oil was not replaced, because on previous services I would feel the performance improvement after service. They have charged me R500 and something to replace the radiator cap, the price of radiator cap is R300 and something, then the other balance is for fitting it (how do you charge fitting of radiator cap). I was also willing to proof by purchasing oil then we re do the monitored service, if the performance does not improve it will be my loss, then if there is any improvement. They must reimbur*****t me.

Anyone at Kia head office please help, before my car breaks the engine.