As explained I sheared one in the arm when refitting and thought it would be easier to drop the roll bar on one side to improve access to the arm, all was fine till refitting the bolts and one of those sheered, needed to remove the whole bar so could access that one sheared bolt, the other two bolts on the other side of the car were unwinding lovely and both sheared after about 2 turns.
used the new improved access to fit the new arm on that side then tackled the 3 sheared bolts in the subframe.
annoyingly the one sheared in the arm easily unwound with some grips which i wouldn't have been able to do with the roll bar in place as it was blocking access to that bolt.
Now I suspect you probably won't read this all the way through or this far as its unusual for you to read anyones posts so can start drawling on, you probably shouldn't have asked the question, so anyway at this point i had a cup of tea took the mini down to the motor factors bought a packet of drill bits some stud extractors and a can of plus gas which came to about £20 ones id started finding other things I decided there and then i needed, drove home had another cup of tea, got out the drill and decided to drill the bolts out,
the bolts only allowed me to drill 4-5mm into them before they hardened up with the heat and many hours and many drill bits where wasted trying to get further before neighbour intervened.
hope this clears things up
the moral of the story is these bolts are stainless steel so don't touch them unless you 100% absolutely have to because chances are they will break and swearing will ensue