I began filing complaints with the proper authorities after speaking with the FBI. These included the USPS, FTC, FBI and NYPD.
I had been documenting odd experiences, such as the theft of my apartment key (and copying) from my office, unmarked vehicles (lacking license plates) parked outside of places where I was staying, mail theft and tampering, and spam calls. I noted in my complaints that I believed that these actions were being taken by people hired for surveillance related to an employment dispute.