[JonnyA]

Feel for you on this - They certainly don't / do not want to understand.
Stick to your guns for a full repair (new engine) in your car.
You've had it from new, built to your spec. No doubt you've looked about but autotrader only has a couple that broadly match (age, milage) at £12-13k add in that (to you) these are wrong colour/spec & unknown and the cost to the insurer of the new engine isn't going to get close.
Unfortunately it could be time to warm up the legal beagles on your side - wishing you all the best on this & hoping they play ball.