You can try the warranty route if you like but you had to fight for corrosion rectification under warranty when these were new, now that they are old I personally don't think you stand a snowballs chance in hell. I'm sure others will agree.
Good luck if you do decide to try.
If it is your spring perch snapping off of the chassis then I believe there is a specific repair piece, and from what I can recall it isn't so much rust that causes this but a stress fracture of the factory weld, and surprisingly easy to repair, I think MB state to rivet it back in place. I could be wrong as I am only quoting from memory, I,m sure their is a thread on the forum about it somewhere, though I believe the O/P riveted it in place then to be safe run a couple of stitch welds to make doubly sure.