Mercedes trying to drive my car out of motor plan

Hi, I drive a Mercedes benz that I bought at New Vaal motors in veeriniging. My car has been having 2 types of noises that were never fixed. The first one started in June. It is a whistling sound in the engine which sound like a fan belt. I took it to them twice, guess what, they told me they don't hear anything. The sound is still there.

Last month i noticed 2nd sound under the car. Took it to them, they told me it's the control arm and said they changed it. The sound is still there. Took the car back on the 7th of December, they initially told me they hear nothing. Drove around with their technicians, they heard the noise. Then the told me they found nothing and they think it's the rims. How stupid is that. 3 other companies told me it's the transmission box. My car is now at 99000km and is about to go out of motor plan. Mercedes wants me to pay. That's why they don't want to fix my car. Please help.