Auto Insurance Claims: Backing out of parking stall, parking lot accident, parking stall

Question
Hello, recently I was in a parking lot accident. I was reversing out of the stall and got about 3/4's of the way out of the stall when I noticed the person opposite me put their vehicle in reverse (due to seeing the reverse lights go on). I stopped, and before I could move or do anything that person reversed and hit my vehicle, addmiting after they did not see me. I got a witness stating that my vehicle was not in motion at the time of the accident, but regardless the insurance company is trying to claim it as a 50/50 accident. What is your opinion?

Answer
Depending on the credibility of the witness, it is winnable.  A witness is golden.  It is common sense, you know?  What if your car had been a child just standing in the wrong place?  If both were in motion, different story.  If you can prove you were not moving, you win.

JP