Contract Cancelation

My husband paid up and canceled his contract with Cell C beginning of January last year but when he went to the bank to check his credit score it showed that he is in rears with cell c and that they handed him over. He went to almost all the cell c branches in pe and all of them told him that according to their systems his up to date and that the contract is no longer in existence, but he should contact cell c legal to clear his name, He has been doing that for the pass 3 months and they keep giving him references and tell him they will phone him back but then they don't call at all. All he wants is his name to be clear.