After speaking with them several times about not owing any amount, I finally sent the FAX (as they requested) to stop the calls. When I originally asked for their address to send a letter (certified), they just laughed and only gave me the FAX number. Since then, they have stepped up the pre-recorded calls (which were coming 3 times a day and now come 5-7). Blatant harrassment at this point.
Caller: recorded message