Very poor service at montus Nissan centurion

Been servicing my wife Nissan extrail at Montus Nissan centurion but my last experience is one to forget, December 2025 the car went for Major service but early March the fan belt came off, when it was checked the mechanic told me that it was because of pully also the belt is worn out. My question to them was how did they not pick out that the fan belt was worn out as I believe they do inspect the car when it goes for service, the they response was they don't inspect the fan belt,for the people that I have trusted my wife's car for more than 4 years , I don't know who should've picked up that the fan belt need to be changed, someone called me after they say they will investigate and her feedback was it been 3 months since the car was serviced there's nothing we can do.