Thing is in total I've paid nearly 15k including everything I've done to it, so that would be what I'd want negotiated for. I suppose 15 gets much closer to an example I'd be happy with.
I’m afraid you are going to need to prepare yourself for the harsh reality that if this car is written off you will get nothing like what you want from it. You overpaid for the car in the first place – I sort of understand why you did this, but the fact remains this is what you did. You paid several thousand pounds over the book price at the time to secure the example you wanted. You’ve then subsequently poured quite a bit of your own money into preventative maintenance and cosmetic repairs etc which is great but won’t be factored into any reasonable valuation of the car. The retail value of this car is below £10,000 and an insurance offer of retail value is likely to be considered fair and reasonable (Infact if anything I’d expect the first offer to come in around £8-£8.5k and obviously should be rejected). There is nothing to lose by pushing hard for more than that and obviously you should try if the situation presents itself, but if you expect anything like £15,000 you are going to be even more disappointed than you are currently.
This absolutely sucks but it’s how it works. It’s also why I always used to worry about somebody running into the 530i – the fact I had meticulously maintained it and it was truly immaculate would count for nothing and I’d end up with a settlement not nearly big enough to replace it with something as good.