Unprofessional conduct and serious harassment

Mbd is constantly calling me at the office, speaking to anybody they reach and placing my employment in jeopardy. They have not provided details, but constantly harass everybody at the office. When I request a call after office hours, the answer is that they do not work late. I sit in an open office and am prohibited from having personal conversations. What recourse is there against such unprofessional behavior and harassment?