Rejected car insurance claim

I got involved in a car accident with a truck at an intersection. I was on the lane turning right, while the truck was on the lane going straight however wanting to turn right as well. I was waiting for traffic light signal while the truck driver drove into the intersection and the back of his truck made contact with my vehicle. He referred me to the truck owner and she referred me to her insurance. I submitted all the documents that were requested. I was then informed that my claim has been denied "due to my statement and that of the driver not corresponding". According the insurance I was "trying to overtake the truck". I requested the broker to relook into my claim as I was not satisfied with their feedback. I was then requested to submit an "independent witness statement". This has been very difficult for me to do. I was with a passanger on the day of the accident who could have assisted with the statement, however I was told that his statement will be "biased".