Mercedes-Benz International review: Faulty back shocks

During the maintenance plan I complained multiple times about a knocking noise left back. Mercedes Centurion would indicate that they could not detect the noise. Now 20k km out of maintenance plan, I'm informed by a reputable shock testing company that both rear shocks have been faulty for quite some time. Cost is about R10k. This experience really has put a damper on the Mercedes quality experience