As far as I understand it the valuation certificate is only valid through the TSSC club and Footman James because of our special relationship with them
(eg the scheme). Other insurance companies are under no obligation to recognise the value. If you are having problems you should talk to Footman James
and they should be able to fight in your corner.
Unfortunately, additional modification or improvements can't count for anything unless you've declared them and had the car revalued.
However, I am not an insurance expert and this is how I understand the system to work. FJ will put you right - I'm sure.
I was lucky enough to be hit by a Norwich Union insured driver (100% his fault), they agreed to uphold the agreed value £4500 and allowed
me to use my own repairers. Good job too as the damage was £2100 worth.
NiG
http://www.niginthecar.net