Bad mechanics

After taking our vehicle to Hyundai Polokwane for a service last year we asked them to check there is a noise coming from the back, they did not find the problem. Today iam.in holiday and that noise is even worst so we took the car in to car service city and it cost me R11000 as the shocks and the shocks mountings needs to be replace. When i asked Hyundai the vehicle had stil warranty but because of poor mechanics i need to chop of with payment of such a big amount