MRS calls from multple numbers Claiming I owe a debt ( cash advance) from 2017.

This collection company is calling repeatedly stating I owe a debt from 2017 for a payday loan made by LV funding. I paid LV funding many years ago. I have not taken any payday loans since 2013.  It appears that this original loan was in 2012-2013.  I explained this over and over, they do not listen.  They just repeat you owe this loan. I assume that if there was a valid debt, I would recieve a written notification. I never have recieved any written request for a loan.  They call from various numbers- including from my area all times of the day and leave stern messages about this  'important matter'.  No one identifies themselves by name and since they have been calling for 25 days in a row.