numerous phone calls from Navient

Receive numerous phone calls from Navient. Have asked them multiple times to stop calling and have informed them that the person they are trying to reach no longer has this number. The number they call on is used by me for business purposes only and is covered by my company. I have asked to speak to the Supervisor of the group to get this resolved on two separate occasions [in early December 2012 and today, January 2, 2013]. Both times my request was refused by the Customer Service person. I do not have the person’s name that I spoke to in December 2012, but the person that called on 2 January 2013 was named Joy.