Harassment from agents

This company has been harassing me for more almost 4 months. They call me at least 3 times a week. They keep phoning me, asking me to a certain individual that I have repeatedly told them I do not know and have no connection to.

I have advised them several times that they have the wrong number and to stop contacting me, yet they continue to call me several times a week, asking for the same person that I do not know.