Listed for unknown account

I have settled all 3 contracts I had with Cell C and confirmed twice that they have all been settled and cancelled. For a year now I enquired with Cell C regarding this account reflecting on my credit profile as acc nr: *** and on my last enquiry I was referred to the Cell C legal department and they too confirmed that I do not have an account with them and this account is just reflecting like that because I have prepaid with cell c. I checked my credit profile again on the 05/01/2016 and Cell C has now listed this account as a default. I have decided to take this matter up with the credit ombudsman as this is an ******** listing and Cell and am not getting any joy with Cell c in correcting same. <br>