Hyundai Service Centre - Car not repaired

I had given my car mh** Hz **** Santro for regular servicing on * March. After that my car started giving me a lot of problems. I told the company they saw it and started giving me different reasons each time I told them that I have a problem with the car. I spoke to the head of the company. He said that it is because of the noise of the tyres. He changed the tyres but the noise was still there. Then he brought another car and then he said all the cars have the same noise but my car was not having any noise. When I gave it for servicing the first day when I drove after servicing it was giving jerks then sounds come from the brake pad which they have changed. I complained customer care also but they are not taking any actions. I am following them from the last ** days. Please help me.