Sorry to see that damage. I had a similar issue with my insurer over a shunt in my Jag. They decided to treat it as a commercial write-off (admittedly, the repair shop quote was £7,800!). I told them I did not want to have the car written off and treat a scrap dealer to an early christmas! After a bit of discussion with them and the repairer, the insurers then said they could settle directly with me and it would be my responsibility to pay the repair shop. I asked how much they would contribute and they said £6,500. After some dialogue with the repairer to trim out some fat, I got his price down to £6,800, so it cost me £300 plus my excess (it was my fault!). This also meant that the car never got registered as a write-off. In your case, the difference and excess would be covered by the other guy's insurance, which Britannia should get back for you.