I did a thread a while ago about this sort of situation, if its not your fault then there is no need to even contact your insurance, they will in most cases give you a reduced figure as its already had a previous payout, but if you had gone direct to the other party's insurance you would recieve full market value. I know this is a bit late in the day for you know but give my good friend Mark a ring on - 08081782110. He is a top solicitor and specialises in RTA's, he has helped me out no end of times in the past and im sure that he would be more than happy to quickly go over your option on the phone. Say I passed their number on, im promise all your questions will be answered within a few moments.

Hope this helps mate