Third party claim rejected with ridiculous reason

A set of robots were out of order last year and treated as a 4 way stop. I was the first and only person at the intersection when I came to a stop. I made sure right and left were clear and when I proceeded to turn right I was hit so hard in my rear passenger door by a car that did not stop that the force caused my entire door to dent in and spin around. I was already more then half way across the intersection when I was hit. I put in a third party claim against MiWay and received a response 2 months later that their client changed her mind that I collided with her (in other words my car moved perpendicular to the direction the wheels travel in) Her police report states that she slowed down and does not state that she stopped even. It's impossible that my car could have been at fault. The accident picture from both parties is not disputed and the damaged caused is not disputed. All of a sudden they are now claiming that their client changed her story and my car somehow, against all possible physics moved sideways and caused such a force to spin me around and destroy my rear door. Claim ref number C567673. They now state that if i don't produce a witness I have no ground to stand on