Incompetence

We bought a brand new Polo Vivo Maxx. The car ha been at the dealership three in two weeks since purchase, for rattles evoking from the rear and the alarm that keeps blowing. According to the workshop foreman there is nothing wrong with car and he refuses to work on it further. The dp also came to me and said that I am irritating the techs. So I took the car to another dealership and they were able to find the faults with the car! So how come they were able to and silveroaks not? I've heard this dealership in sales three times already. Is this the way they treat customers? We only have Vws at home all of us are getting rid of our cars asap. Thanks for nothing vw silveroaks.