If you have records and there is a lot of phone calls etc you can go to the commissioner at your local court house and ask that harassment charges be filed. You will need detailed info/evidence. You can possibly go to district court and seek a peace order if the harassment is overwhelming.
You can also get the phone company to block numbers. (and keep track of numbers/calls).
This response is based on information provided. Many variables may exist that can only be addressed in an interview. This answer in no way creates an attorney-client relationship.