When I bought my Golf last week, the chap I bought it from had it MOT'd by the VW main dealer - who originally failed it because the exhaust bracket at the very back of the car (attaches to rear silencer) had detached itself from the silencer box. Strange that its done this as the exhaust system looks in practically new condition.
They welded the bracket back on and passed the car.
This weld has lasted only a few days and broke - on looking at it closely, the weld has been done with a MIG and has taken to the silencer but not the bracket - probably because they did not clean off the surface rust from the bracket. Lots of welding wire strands sticking out of the weld as well.
I am quite shocked that a main dealer could do such a shoddy repair - if thats the standard of their welding, I would hate to see a repair on an older car when a structural weld (say to a sill or chassis leg) is required

I fixed it properly myself tonight - if you want a job doing right - do it yourself! Just glad it was not my money that was passed to the dealer for this work - I have the bill in with the service documents as well - £30 for nothing.