Constant calls about a unpaid balance

The first caller did not identify the company name, so I thought it was a solicitor or a scammed. Afterwards, I blocked the number. Early  Saturday morning, ring on the cell phone from a caller that get to the pointwhen I ask questions about  the call. The questions started with what is this about,  why are you calling me, she answered of course proudly with the name of the company and the amount  owed.  I have documentation to the contrary. We have to shut them down, because  this is ridiculous, unlawful and just plainly  trying  to obtain money fraudulently.