Harassment

We are being hounded by U.S. Pharmacy 4 or more times a day.  They even found my cell phone.  Can't we sue them? Even if we don't get a penny, arrest them for harassment.  We are absolutely furious that our time and privacy are being abused in this manner.  Each time they call I tell them we are in the process of suing them and at least they hang up quickly.  Who are they.  Why are they allowed to call after we tell them to stop?