This account is affecting my credit score!!

This company im really not happy with their work ,i had a ********** account that was opened on my name last year . This company said i must send them copy of my ID and Affidavit i did that ,now im getting endless email that i owe Cell C .yersterday i called the guy said they are still investigating the matter .And this account is affecting my credit score. Please help Reference of the case is Cell C Account, ***