[legion]

Not quite the same, but I did have a memorable experience with unsolicted phone calls:

During the spring of every year I would get repeated calls from a professional fund-raising company soliciting donations for the Fraternal Order of Police. They purposefully use gruff-sounding males to make you think you are talking to an actual police officer, though if you ask they will admit they are not. I repeatedly asked to have my name removed from their list but they insisted I had no such right. Sick of the fifth such call in a week, I simply said: "I am involved in a lawsuit with the police department (not true) and I don't think that donating to them would help my cause. I never got another call back.

My point is, start asking them questions. Get as much info out of them as possible. Ask what the name of their company is, where they are located, the name of the person you are talking to. Explain (again) that you are not the person they are looking for and that you are trying to build a harrassment case against their company. Get a lawyer friend to send them a letter on company letterhead insisting that they desist.