Is my Wisteria dead?

Hi Folks

I have an established Wisteria that I believe to be about 80yrs old. 

2yrs ago I employed workmen to redecorate the exterior of my house using traditional lime wash.  The Wisteria plant is rooted in the ground, surrounded by stone slabs around the base of the plant.  During redecoration of the house, the workmen inadvertently covered the Wisteria in lime wash and severely damaged the Wisteria by breaking off almost all of the flowering branches.  All this done having giving me assurances that they would try their very best  to take extra care.  Frustrating!!

The following spring, the flowering branches were healthy and numerous buds appeared on the few remaining branches...only to be caught in a late, severe frost. 

That summer, the Wisteria plant shed it's few leaves.  I remained hopeful, believing my plant to be dorment; however, this year the plant has failed to leaf and produce flower buds.  The Wisterias thick branches appear brittle and dry to the touch.  

The Wisteria was a feature of the house and I would very much like to revive it.  Being realistic, I now believe that it may have died.

If the plant is dead and the aforementioned account is not enough to kill a Wisteria, then I would be extremely interested to learn how such a healthy and established plant met its demise.  Has my Wisteria been poisoned?

This is really concerning for me.  Any advice would be very much appreciated.  Thank you.