Door Panel discoloration

We bought a new black VW Polo sedan in 2013. 3 months later the black center panel in between the front and back door started discoloring and becoming a dark green, emerald color. We contacted Lindsay Saker in Greenstone and they informed us that it is a manufacturing problem and replaced the panels with no hesitation. A few years later and now the panels have done the same thing. We reported it to Adolf at Lindsay Saker Alberton when they did the 30000Km (before the warranty expired) and he said he would look into it when we take the car back for the 45000Km service, which was in January 2016. Adolf had the car in Jan for the service and we reminded him over and over again about the panels. He said that the car is now out of warranty but he would contact his boss and he would let us know, but i could collect the car it was ready. I took a half day off work and rushed to the dealership when he informed me that they had no stock of the v-belt but I could 'pop-in' at anytime DURING THE WEEK to have it fitted...Seriously????? Adolf has never contacted us back even after numerous messages left with the receptionist, and now we get told that it is not their problem. FIX THE PANELS!