Dispute with insurance value! Can anyone help please?

[triumph2.5pi]

Hello all
My insurance company has written off my 2.8 Sport They have offered me less than half what I believe is a reasonable retail replacement cost and are currently refusing to budge.
I have a Parkers valuation, but they won't take that into account, being a 'consumer' guide.
In order to strengthen my case, I could really do with CAP and/or Glass' (preferably both!) 'Retail' values weighted for milage and options. I believe you can only get these as a motor trade professional. Does anyone have access to these, or know someone that may be able to help? I would be very happy to pay for the trouble!
Thanks :-)