I think i broke mine a few years ago, but i still cant say if i broke the nut welding, or the bolt itself.. I just left it there and didnt bother with it, since i didnt really need to take out the assembly..
But, i did broke the welded nut on the rear engine mount (f23)..The mount needed replacement, and that -censored- broke, i was stuck with a bolt spinning free and keeping me from taking it out..
Since i was doing this at home, and the grinder was too big to fit, i had to dremel-out the head of the bolt.. Took me about 4hrs, and i had the bright idea of not wearing a breathing mask..Spent the evening tasting metal, and the next morning coughing blood (well just a few times, but enough to scare the **** out of me!!)
When i finally managed to take out the mount, i had to make a hole in the subframe to take out the scrapped bolt, and fit a new nut/bolt assembly. This, was one of the worst episodes in my DIY carreer.