That is very good to hear thank you! I was fairly certain it must be a common issue in the specialist vehicle world, but unsurprisingly the insurance company were not keen on the idea and I had not come across any other stories on my, all be it limited, searching on the subject.
I have just had what has to have been the nicest, most helpful, and most competent call with the insurance company, unfortunately I did not get her name but head and shoulders above everyone else I have spoken to so far! They have agreed to hold off reporting the category to the dvla until I have retained the reg and have the new V5 which on current DVLA timeline is 4-6 weeks, they were quite happy about the time because "it is the DVLA". At least even if it stays cat B I will get to keep my reg, which although nothing special and not personalized is part of what makes it my one if I do need to start again and rebuild. Also although I have not yet heard from a "Team leader" the complaint challenge is logged in the system and being processes all be it slowly (a benefit atm) and if I get the independent report and submit that it would aid my challenge.
Does sound a bit more hopeful.
Our assessor, who had to be shown where the accident damage was, cos it was so slight, simply wrote on the form.
"The slight damage I saw could not have happened if the accident had happened the way the third party insists. It would in fact have been far more extensive."
After a few years of the insurance company batting it back, the third party paid for his own barrister to take it to court. The judge, the court offices and our barrister fecked it up like you couldn't believe. This piece of paper went missing and the judge awarded against us. But our insurance company knew the accident was not Wifey's fault. Paid up cos they had to, but didn't put Wifey's premium up nor did they remove any of her NCD.
I contacted the judge and the court after it and they admitted that the paper was in the judge's bundle all along.
So the thick fecker knew he'd made a mistake.
Nothing like your case at all.
But if you'd seen the damages the third party was claiming for, you wouldn't have believed it. So yes, your own assessment should help loads.
And I sincerely wish you all the best with it.
Having been there, in both the question of a vehicle fire and a lousy assessor, I really do feel for you.