I'm sorry this has happened to you. When I lived in an apartment once I was sound asleep on a Saturday morning and was awakened by someone opening the door. A new employee had mixed up my apartment with the show apartment next door and was bringing prospective renters in. My screaming in my pajamas probably scared them off..........then several months later the maintenance people came a few minutes before they were scheduled. I had my hair dryer going and didn't hear them knock so they let themselves in. For whatever reason they did not leave or yell that they were there when the hairdryer stopped. Again I screamed in terror at strangers in my home unexpectedly.

I don't know a solution (I moved but that was for a new job) but wanted to tell you that you are not alone.