What I want to know is, if it's caught on dashcam like you say, then why haven't you uploaded the video so we can judge for ourselves on what happened? A still picture of a car (not even in the act of committing the offence you are describing) is absolutely pointless...
Send the clip to the company. He needs to know that road rage can have consequences. The idiotic braking could have caused a serious accident. As a professional driver he needs to calm down.
Have seen this car driving around the Windsor area at excessive speed and rather dangerously.
Have reported to the police..