Had this issue as well. Did send letter making them aware of lease violation and that any other incident would result in lease termination. Here is the letter I sent. Hope it helps.
Dear :
I have been notified of your aggressive and threatening behavior toward my Assistant Manager on Saturday, July ______. Behavior that caused her to contact our Courtesy Officer.
She apologized, as do I, for the delay with your electric concern. I was informed that you had been informed it would be addressed Saturday and it was. However, there is no reason acceptable or will be tolerated by this office when you threaten my staff, as witnessed by another staff member.
As stated in your lease agreement / Clause 14 – paragraph 10, “Resident and Resident’s occupants, family, social guests and invitees, shall act and communicate with the apartment owner, Management, Management employees in a lawful, courteous, and reasonable manner. Any form of verbally or physically abusive, intimidating, or aggressive behavior directed to Management, Management employees, or any other person is prohibited”.
If this occurs again, your lease will be terminated without further warning. All early termination fees and rents due will apply. If you have any questions, please feel free to contact my office