How to report a reckless driver?

I was just driving on County Hwy CV heading westbound from Hwy 51 between 9:00 - 9:10 pm CST when I had to slow down for a turn. In response to my reduced speed, a person driving an AT&T pickup truck behind me turned their high beam headlights on and left them on continuously. The driver then proceeded to get recklessly close enough to my car that it triggered the rear proximity/parking sensors three times. When I got in a right turn lane, the driver came to an almost-stop in the middle of traffic in order to give me the middle finger which is when I saw the AT&T logo on the door. I was not able to get a vehicle number or license plate number however, it should be possible to identify the driver via GPS given the time and location. This was completely unprofessional and downright unacceptable. Considering the frequency of animals crossing the road in this area, this driver could have caused an accident a total of four separate times within a matter of a few minutes. 

I tried to call customer service and was unable to reach a live representative.