Poor car service

I recently took my car to Car Service City for its 60 000km service. Everything was in order, it was just due for a service. In addition to the regular service items they adviced me to replace the alternator belt along with the aircon belt. I accepted the replacements but was hugely dissatisfied when driving my car again. It was making terrible squeaky noises coming from the belt every time I pulled off along with reversing. When using the aircon, the noise was unbearable. I returned and they looked at my car again. This time they couldn't find any fault and told me i needed to repair a pully from the aircon. I have driven over a week now, not once using my aircon but hearing that loud noise every single time i use my car. I am hugely dissatisfied with their incompetency of acknowledging a mistake on their part and properly fixing it. After all, it did not make any noise before it went for its service! In addition, on a previous occasion I had Car Service City fix my car whereupon I also had to return twice before everything was done correct.