third party claim rejected ********ly

I was driving on the left lane on a 4 way road (two lanes heading same direction and other two lanes heading opposite direction). The other car which was driven by a lady (insured under outsurance) was on the right side of the road heading the same direction as me. As I was nearby to pass the lady's car, she changed lanes from the right (where she was initially at) to the left (on my side of lane) without indicating, I app**** brakes but the car was already too close and I bumped to her car's back left. We made an accident report where she indicates that she changed lanes and missed my car in the blind spot . I launched a third party claim through this lady permission (Claim No. (***). Claims advisor sent an email saying they reject my claim because their clients said she was already in the left side of the lane before the accident. I totally feel cheated with regard to this claim, as the facts made on the accident report by this lady is actually what happened, but the letter that I have received from the outsurance totally contravenes what transpired on the day. Outsurance please use the Accident Report for analysis not your own stories. My next stop is ombudsman!