I have had situations where i have been followed in some shops and gave them a very stern look and eventually they stopped.

Another situation was where I was waiting to be picked up from the beauty salon and a man drove past me over 5 times to stare at me, pulling over to try to wave me over and parking to sit and stare some more. Once he saw my partner arrive to pick me up he was quick to get away from his vehicle so we could not find him.