what can i do to stop a woman from banging on the door?

Step out into the hallway, politely ask her to stop. If that doesn't work contact your Local Law Enforcement Agency, and see if there's anything they can do. Also talk to your Complex Management Personnel. They may be able to help. Which may include moving you to a different part of the building.

Hope this helps.

Move. Apparently you're not such a great neighbor yourself, if you are constantly jumping to conclusions as to your neighbors' sexual preferences.

Talk to the landlord/manager, tell him/her that your neighbor's friend is depriving you of the peaceful enjoyment of your apartment.

Or you could call the cops, and have her arrested for disturbing the peace. Of course, you have to do it at the time of the disturbance. The woman is probably drunk or stoned, and can't understand that her friend is not there.

Call the non-emergency number for the police department and tell them you think someone is trying to break into the apartment across the hall from you.

Why don't you go out and ask her if you could help her? I know it's not much, but you could tell her you could leave a note for your neighbor and let her know her friend was there. Hope I've helped.

Sounds like she is trying to break into the apartment call the cops and report it as such.