Just to confirm, you were following at a safe distance and within the speed limit? This is not to say you weren't, by the way. Just a means of trying to establish the circumstance. If these people are intentionally driving round looking for trouble then the public and the police need to be aware. I wonder why someone would do that.. well, one can only speculate. Some do it to try and rob people. Some do it for fun. Both groups are are ass-holes who deserve everything they get..
Best thing to do is get it on film. Then upload it well before telling the police? Apparently they don't care?