I had patients with phobias. One woman would get in her car and lock all the doors and go to her job, being sure someone was following her - she felt safe at her job. After her job, she got in her car, made sure the doors were locked and went back home, being sure someone was following her. Got in her house, made sure all the curtains were pulled, checked every lock, turned off the lights and stayed in the dark until the next morning and did the same thing that day for day after day. She also had a recurring dream. Once we debunked the dream as not true, the phobia was gone.
One has to find the core reason for the phobia, then dismantle that reason with truth and fact.