| The first one I have heard of in nearly 6 years
You'll have to remove all the hub components but replacing the shaft should be that large a job, mercedes of course will say it's a big job and will have to put it on the diagnostics to tell you what's wrong with the car just to back up the bill !
Now if your in the UK you should be able to get hold of a good unit off e-bay plenty of 'A' s being broken at present. make sure you get the right one because one side is split into two shafts | 
