This is called "slamming" - and it's illegal. If your local or long distance service is switched without your permission, please Contact Us and we will restore your service.
You may also want to report the incident to either your local Public Service Commission (please call 611 for the number), or call the Federal Communications Commission (FCC) at 1-888-CALL-FCC (1-888-225-5322) or go to www.fcc.gov.