LGC help - snapped a tap

Hey guys, need some help to avoid buying a $315 trailing arm for my
BMW...
 
I was chasing a thread in the trailing arm when the tap snapped in two.
I've tried drilling it (hardened steel, dulled my drills), and I've
tried to rotate it out by tapping on the flutes with a nail set (bent
the tip of my nail set). There's nothing sticking out that I can get a
tool on to.
 
Any ideas?
 
Thanks!
 
Chris
Chris King 
http://home.comcast.net/~kvcbk/