Car Service Damaging the engine during Major Service

I have been service my car with Car Service City for the years now. I then upgraded my car with a new one. After few months I took it for Service with the same Branch (Ormonde) for major service, few hours after leaving the centre, my car was making a funny sound from the engine which it was not making before. I then call them and sent an email first thing in the morning complaining about a sudden noise. They then requested that I bring which I did immediately. They checked indeed they found noise and sprayed a belt which temporarily went a bit off. They told me to call and book the car again for specialists when When I get a bit of time. I came back and they checked the car which stayed for over a day at the garage. They then gave me feedback that It is the Aircon Pump which needs R6500, no longer V belt. Other Experts from the same yard expressed the view that it is not a pump that is making noise. The branch still continues to say that they cannot take a full responsibility with the damage that was caused by their sound. Despite the persisting sound on the car which also afffect fuel consumption. My argument is that, the car came here without any sounds. They also did not pick any of that in their diagnosis report but after touching the car, the car started making a funny sound. She insisted on taking us to his other expert to verify and check the problem ( HF) , her expert said that the car does not have pump problem she should check what the problem may be. I have spent a lot of petrol and time running to this branch and the so called Branch manager does not one to take a full responsibility and fix whatever that they may have damaged during the service. Her mechinics on the side, testified that indeed the car came here without any funny sounds. The sound is still consistent and rather getting worse with the noise. I really need your intervention with this matter. I just need my car to sound like it used to before bringing it for service. Nissan Juke Owner