Global Crossing Telecommunications Unauthorized change to long distance telephone service from my AT&T account to their name Internet

To Whom It May Concern

Today I found that my long-distance telephone service has been changed to Global Crossing Telecommunications on my AT&T account. I did not authorize this change.

I checked in the Internet and found that another person had the same issue with this company and he has already reported it.
http://www.ripoffreport.com/Telephone-Companies/New-Century-NOS-Glob/new-century-nos-global-cross-a8a35.htm

Can somebody stop this company from doing this: Unauthorized change of telephone service from reputable companies.

Thanking you..