Faulty workmanship

I took my Duster for a cambelt service at Renault Centurion. After a year there was a bad noise. I took the car to another Dealer. They had to replace the whole kit because of bad workmanship. After another R7 000 Centurion just say it is not their problem and the service manager asked me why did I pay. I wonder if I will buy a Renault ever in my life after 20 loyal years.