FTC

http://abcnews.go.com/US/wireStory/study-35-percent-us-facing-debt-collectors-24752030

"More than 35 percent of Americans have debts and unpaid bills that have been reported to collection agencies, according to a study released Tuesday by the Urban Institute.

These consumers fall behind on credit cards or hospital bills. Their mortgages, auto loans or student debt pile up, unpaid. Even past-due gym membership fees or cellphone contracts can end up with a collection agency, potentially hurting credit scores and job prospects, said Caroline Ratcliffe, a senior fellow at the Washington-based think tank."

 If you have a complaint against a cellphone company and their debt collectors for fraudulent, harassing business practices, then file a complaint with the FTC:
https://www.ftccomplaintassistant.gov/#crnt&panel1-1