Sorry to here about your car mate that sucks.
Insurance companies will do whatever they can to get out of paying a claim if they think they have a legal right.
Telephone the insurance company and ask to speak to the claims underwriter dealing with your claim. Ask them to reconsider, if they dont ask to speak to the senior underwriter in charge of that department, dont take no for an answer.
Ask him to reconsider, if he doesnt, mention that you are prepared to take legal action through your solicitor, and also take the matter up with the press.
If he then refuses to do anything immediately inform him that you wish to make a formal complaint over the telephone, they have to by law make a note of your complaint, follow your complaint up by in writting by recorded/special delivery the same day.
Once you have done all this and if they still say no then you need to make a complaint to the financial ombudsman :-
Dont expect anything to happen to quickly it can take some time.
If you can, record all your telephone conversations with the insurance company. You must by law infom them that you are doing so as soon as you start your conversation.
Most insurance companies record all their telephone conversations, if this is the case once you have sent them your written complaint, also write to the insurance company and ask them for a transcript of all your telephone conversations, noting dates, times etc. They will be reluctant to provide you with this, but they have to by law. (This will add to your case if you have to go to the financial ombudsman).
Make a note of every telephone call you make, get the name of every person you speak to, including surname, and document ever peice of correspondance with them.
Good luck, and don't take no for an answer with them.