From my own experience, they always offer a low amount
1st you need to get a quote to get it fixed
there are 4 options you can get from an insurance company
1, Write off , and option to buy back
2, A cash amount up to a % of it value, often more that the fixing amount as they work on
unexpected costs, and the car is not written off, you pay to have it done where you want and can use second hand parts, they also refund the VAT on new parts
3, They fix it , to do this you need the quote, write down what is good about you car, and unique say mileage , version, now find some on autotrader etc that have the same spec as your list, remember , you will need your car is not one of the £100 ones but find one similar with a realistic price and print it and forward a number of them to the insurance underwriter, and explain why this the same as yours, maybe colour, mileage, condition, you will need to most likely that 3 or 4, remember someone wants £50k may not get it so be realistic
4, Ask for a replacement,
The law states they have to place you back in the same position you were in before the accident, not less , not more
Simon