Time wasting rude and *********** callers

I keep getting phone calls from various people from MDB Attorneys wanting to speak to a former employee of mine. I have explained to the few that stay on the line that he no longer works for me, i don't know where he is or how to reach him. The calls are getting out of hand now, sometimes 4 times a day, after hours and weekends. I don't see the point of calling me constantly, you are wasting your time and mine. I have asked many times for my number to be removed from your data base to no avail.