Complaint Review: Penn Credit

This company keeps harrassing me with phone calls (how they got my number I do not know) about bills from Mountaineer Gas at my current place of residence.  I have lived here for over four years and my gas is paid for in my lease!  I have explained this to them time and time again, they claimed that they would send over papers for me to fax information to them (which I have never received), and they just keep calling!

I have given the number to my landlord to take care of this situation, but apparently they feel they need to harrass me and my wife.  If it keeps up, this will escalate where I truly go off on the phone and they will not like the words that come out of my mouth.