Unhappy with service received

I bought a new Hyundai i20 in 2015 June. And since from the first service of 15 000 I have complained about the rattling noise that the car makes when going over humps or potholes or even uneven surfaces. They told me it was my stabilizers that needed to be lubricated. A week after the service the same noise again. I reported thus for the next two services after that and I am still sitting with the same annoying noise. 3 weeks ago it went for the 60 000 services and still reported the same problem but nothing. They claim they can't hear any noise. I have taken the car back now for a clutch kit fitment and reported thus to the DO Mr Foster. He promised to look into this. So I am hoping that I get some joy. I even spoke to the sales people in Vanderbijlpark where I bought the car and they told there is nothing they can do. So disappointed in Hyundai after sales service. As a first time car buyer no one explained that or advises that I should also buy a maintenance plan together with the service plan for the vehicle. So now I am stuck with a service and looking forward to a huge bill of replacing wear and tear parts like brake pads etc. Not happy.