Naked Insurance did me wrong

I'll give naked one star, Im not happy with them, all was well, submitted my claim and all but, they undervalued my vehicle and now Im struck with 20K that I owe the bank, to top that, I've been writting to them and they have not given me a straight answer cause they do the evaluation and as a proper company, one would expect that you can evaluate a car and I did inform them that the car is white metallic silver but they treated it as a white car. Im not happy tuu, where am I suppose to get 20K, hayi nina