to big,
you snapped the head off the bolt right, and the jamnut is loose.? all you have now is a portion of threads showing.? well it's trashed now anyway, i hate to say it but, grab the threads directly with the jaws of visegrips or channelocks back it out this way, replace the adj bolt with a similar length replacement, metric of course.
** the ez-out bit will work too, provided you can get a straight hole drilled to turn the extractor. don't let that kinda thing slow you, jdv500