Littering and causing Havoc on the Roads

KD 61 PH GP the driver's passenger threw an object out of the window hitting my car and the car behind me. The car behind me probably thought I through the object out of the window, because he started tailing me and driving up on my car placing my life in danger. I had to show him that my windows were closed, and I couldn't have thrown the object. I'm absolutely shaken and disgusted due to the stress this has put me through. Your drivers are terrible as this was not the first time they have caused havoc on a road. This happened in Hatfield on the road to the N1. I tried emailing them, but the emails bounce back. Terrible, how they are still in business is a wonder.