Kia Pinetown : The worst service I've ever experienced

A little over 2 months ago I dropped my car off at Kia Pinetown for a 15000km service and I explained to the consultant that I'm hearing an unusual sound ( like it an old car) when I'm driving and my gear keeps getting stuck. She said it probably because it due for a service. After it was serviced I could still hear that noise so I took it back to the service center, this is 2 weeks after the service. They told me there is something wrong with the gearbox and they needed to change it. I could not understand how was this not picked up 2 weeks earlier ( but okay). I had to fight hard for a rental car and I only received it 3 days after I dropped my car off. My car was with them for a whole month and during that time I did not receive any feedback from them. Finally, I got my car back and I'm still hearing the noise and the gear is still giving me problems.