Replacement of disc brakes - New Car

I'm a very disgruntled and dissatisfied customer of Volkswagen. I have purchased a new Polo Vivo 1.4 and on 15000km we experienced problems with the brakes of the car. When taken to the dealership they stated that the brake discs needs to be replaced. When asked why, they stated that there are some blue marks on the discs, which is utter *******. This exercise costs me R2547.90. Where in the world do you get firstly that brake discs go before brake pads (nothing wrong with break pads) and secondly how is it possible to replace discs on such low mileage. When looking at the internet there are many complaints about this factory flaw and I think Volkswagen should come to the table and fix this obvious exploitation of their customers.