Hyundai Motors India Ltd — not taking complaints properly to fix the issue of rattling cum whistling as well cooling of my new car

dear sir, I had purchased my new car from ashiana Hyundai patna Bihar on 13th dec 2012. after 6 months I felt rattling and whistling sound from the engine compartment. I visited twice to ashiana Hyundai patna and once at srivas Hyundai hajipur but these isues have yet not fixed.every time they are asking to visit for the same issue to the service centre but they are unable to take the issue .after coming from service center again after few days the same issue is noticed by me.
I feel and afraid that they are misleading me and waiting for the warranty period to be over and after that they will ask me to replace the part on my own cost

advise me what to do