I've owned a 2005 Mercedes-Benz SLK from 2006. It's done 100k miles and is generally reliable. However, it needed the brake pipes replaced due to corrosion and, while doing this, the garage discovered cracking in the subframe from corrosion. They say it needs replacing as it's dangerous. No issues with previous MOTs. Never had this on any car before. Mercedes refuses to help out, saying the car is too old and not maintained in the dealer network. It seems like a problem on this model from the owners' forums. Does Mercedes have any responsibility?