I replaced the front discs and pads on my sons Polo about a month ago.
Recently he had a rattle in the exhaust so I suggested a pro assessment, main dealer, was required because it may or may not be the front section with the cats.
So he leaves the car with a very well recognised main VW dealership for the day.
They phone him in the afternoon and say Yes its the front section that requires replacing but the loose parts may have migrated into the rear section so that will probably need replacing as well................and by the way your front discs and pads need replacing.
So much for honest main dealerships......