Refusal to pay out on insurance claim

I have full comp car insurance. Just over a week ago on the way home from work, I was parked at traffic lights. when I went to pull away my Freelander started over-revving and black smoke pouring from the vehicle at the back and white smoke pouring out from under the bonnet. I managed to pull to one side, exited the vehicle and took my keys out, but the engine would not switch off. To cut a long story short, my engine exploded and I had to call the fire brigade. I contactedmy insurer Bell and explained what I thought was an engine fire, they took the details and sent an assessor out last Tuesday who said it wasn't a fire but that the turbo had failed and literally sucked all of the oil out of my engine, causing the pistons to explode. My car is a right off because there is no bottom in the engine!
I have been in touch with my insurer today who state that since I didn't stall the engine the turbo damaged my engine and since it is mechanical I'm not covered. Now I can understand them not covering me for the cost of the turbo, but since my car has been wrecked by it failing, can't I at least claim for the other damage caused? As for not stalling it, there was a health and safety issue in that I thought the car was going to explode, so I exited it pretty quick. The last thing on my mind was "oh I must stall my engine...". Any help or advice as to where I stand legally would be gratefully received. Is it worth speaking to the Ombudsman? I'm so upset.