Ignored the calls, now I am getting letters in the mail for me to call them?

Have not done anything different in years, and can usually stay out of the target zone for these do***ebags but did recently sign up with a job site in response to a legitimate job.  Bet those folks sold the information

Called 3 times in one day. For 3 weeks straight.

keeps calling my cell phone number; when I pick up, nothing there

They call but no one there when I answer.