wreckless, inappropriate and disrespectful driving

on Wednesday 24th at just after 11h00 I was driving on the m5 changing lanes driving normal and ur driver DC43FD-GP...throwing me lights driving high speed coming so close behind me almost drove into me and my 4yr old son and wife is in the car...he overtook me on the left lane driving extremely reckless and very close to my car and showing me middle finger...does this guy have no training or respect for road users and the rules of the road...im not happy with this.