It doesn't matter how much evidence you have. If glasses says XY or Z then that's it.
Incorrect. They may attempt to fob off the gullible with a trade value, but you're lawfully entitled to be returned to the position you enjoyed prior to the claim, which means they have to pay actual replacement value. Most people aren't registered car dealers, so replacement value will be what the ordinary person has to pay for one at retail or private prices in your region of the country.
My ex wife very kindly wrote off a car for me some years ago. It was a Tuesday.
On the Saturday, three days prior to the crash, I'd agreed and signed a trade-in-deal which valued the car at far higher than either trade or retail prices. The car at the moment of the smack was therefore of far greater value than the price at which it would normally change hands. The small claims sitting of the County Court agreed, and within 10 minutes of walking in I was awarded the agreed trade in value of the car plus legals costs. You're lawfully entitled to be returned to the position you enjoyed prior to the claim, not simply the 'value' of the vehicle - period, as our American cousins say.