New car making a noise

On the 14th of May. I purchased a new car from Mccarthy Vw Constantia. After a month later I heard a noise coming from the back left hand side of my car. I called Mccarthy and asked if I could bring the vehicle in. They advised they fully booked. But I can bring it in on the 11th of June which I did. I was taken for a drive to hear the noise with the gentlemen . He didn't hear any sound and said the car is fine. But up till today I have the vehicle not even 2 months. When I turn and someone is sitting at the back you can hear the noise or sound . I'm not blaming anyone. But is this fair I bought a new vehicle and it's making a noise. I'm just so helpless and dissatisfied and dissapointed.I would like the car to be checked .