How much are they offering? - I'm assuming it's more than the repair bill??
I had a 2 month battle with Carole Nash/Equity Red star, with them offering more and more each time - went up from £3100 to £3800 (for a K4S with new tyres and 7000 miles on the clock). Keep pushing and challenging them and they'll keep offering more.
Can you get to the bike? I visited my bike in the scrap yard and ripped off the hugger and tax disc... only things that were salvageable. If you can visit yours, get the alarm and scottoiler off of it before you accept their offer - it's your bike until you accept the offer. Getting the tyres off might be a bit excessive! Even if you get those bits off, I wouldn't accept less than £3400.
If you can, get some trade ads for similar bikes. I found one very similar to mine (same mileage, year, etc.) and the price was £3900 - close to what they ended up paying. When they look at offering you more money, if you have evidence of how much similar bikes were being sold at around that time, they're more likely to give you more. Above all, don't accept their first offer, act offended and ask for more and you'll likely get it.
Hope you get a fair price for it. And another SV