Your link don't work for me, I had an accident back in Feb, which was'nt my fault(still waiting for money) & it was touch & go as to wether my car was a right off or not.  It was'nt as it happens, but my insurance company said if I did'nt agree with the valuation I needed to show them copies of autotrader etc.  Your insurance payout should be enough to cover the cost of replacing your car.  If you look in autotrader,pvw,golf+ & the like there won't be many cars in the same nick as yours for under 2.5k or more. I'm not suggesting you'll get that much, but autotrader etc reflect the true market value of a car like yours & its market value you should be getting, its worth giving the bastards some hassle.  Good luck dude.
Oh by the way when you come to get insurance again choose a company who do agreed values, like HIC, it costs a bit more but well worth it IMO. Thats what i've done now, just on less thing to worry about.