GC Services Limited Partnership balance due for something never ordered or received Houston Texas

I had an ISP account with XO Communications in 2000. I closed the account after one year of poor service. Three years later I get a collection statement from GC Services regarding my XO account. I called XO to find out why but their records don't go that far back and they were bought out so they can't explain it. I write two letters to GC explaining my situation in 2004 and don't hear back. On June 14, 2006 I get another collection notice from GC regarding the same account. I guess XO figures they'll keep trying to threaten my firm until I pay!

Jeff
Manhattan Beach, California
U.S.A.