I blame my neighbours :-) We bumped into them up top and I followed them on a line through the trees past their mountain chalet, I was skiing fairly quick to catch them up and popped off a small roller, as I landed I thought my ski had released and stepped back in at the toe. Pushing my heel down didn't do anything and when I brushed the snow off, the top of the heel unit was gone. I didn't bother trying to find it in the deep snow.
Maybe the top is replaceable? But, why did it break? If I've worn out and stress fractured that heel, then is the other due to go? I'm tempted to just get a new pair.