I was reversing out of a car park space into a one-way zone. I checked left and then right before slowly reversing. As I was reversing I kept checking to my right as this was the direction of on-coming traffic. A car entered the one-way zone in the wrong direction and we collided. My partner called the police who said the other driver was at fault for the car accident, however, my car insurance company says it's my fault and have to pay the excess. So who is at fault, as I believe that it is not my fault as the other driver shouldn't have been where he was?