I am an unhappy customer

I bought a brand new Chevrolet Utility 1.4 bakkie towards the end December 2014 from GM Bruma. Drove the car home to my surprise when I got home my luggage was full of dust, and when I checked I realise it was coming behind the seats. I spoke to the sales agent who said I must bring back the car to have it checked, brought it back but there was nothing done on the car. I was told dust is coming through those holes and I bought speakers. Had another trip home and once again I had dust coming in, I then called the sales agent to tell him that I am still having the same issue. I had to bring the car back again and this time I was told that the car is meant to bring it dust as I was driving on the gravel road. I then insisted to speak to someone higher than him and a branch manager was called to try and address my issue, however I never got to meet him but apparently he went to the branch. A suggestion was that they will have to borrow one of their bakkies to see if it will bring in dust as well. Got a car drove it home and I didn't have dust like my car, I gave them this feedback. The reason why I decided to buy a brand new car was that I will have a peace of mind.