Police striking feat in law abiding citizens

Last night driving home from a show at Emperors Palace, we were followed by a police van driving too close to my car with their headlights on. I was driving an average of 90km p/h on the highway because of loadshedding - all the streetlights were out. The next moment the cops switched on their lights and I was forced to pull off. I decided to stop at a fuel station for safety. I parked and opened my window, and the driver looked at us, noticing my partner next to me. He is a bit taken back because I'm white and my partner is a different race. He asked if everything is okay, and I said everything is fine. Then he asked my partner, "Is she fine, how many units did she have?" ***?! I told him I had nothing but water, they are welcome to do a breathalyser test on me. They realized that they were not going to get anything out of the situation and left without another word. We left the fuel station, and at the traffic light noticed the same van making an ******* turn at the traffific light. Then they started following another car which turned into a quiet street (a more expensive car, btw, but again the driver was following all the rules of the road). I am insulted, our police force are forcing their authority on innocent citizens for personal gain. I was intimidated on the road by their inappropriate driving, putting pressure on me and then assuming I'm drunk when I did nothing to portray a sense of incompetence on the road because I was 100% sober.