if the policy was in your name, then you are the policyholder. Your policy would cover you for the liablity of your drivers, who in law would be deemed your servents or agents.
From what you say, I would feel that your driver (ex) was totally liable for this incident. you cannot open a door without looking.
he is a named driver under your policy and was entitled to indemnity fomr the insurer.
the fact that he drives a company van does not make that company liable. how could his employer be liable for what he did in a private capacity under yoru policy?
Your only hope, and given that he is your ex, it appears to be quite slim, if to work out how much the loss of NCB is worth and he agrees to pay the difference for you.
Sorry for the lack of hope, but despite what others say about me, that i should only give you the answer that you want to hear, I must be honest and not give you false hope.
You ahve lost yoru NCB and thats that.