What can be done if someone harasses my parents daily?

I am from Gujarat. I am living in a rental house, and my landlord is a good person. However, there is a man in front of my house in my society who calls my father every day, saying that we need to vacate the house because he helped us find it. He has been constantly calling my father for over a month, and my parents are mentally stressed because of this. My landlord has said that we can live here as we want, but this man continues to harass my father. Please help me as I am a student, and I cannot see my parents in this condition.