Credit listing for a contact expired

I took out a 2 year contract, over 4 years ago. Last year I changed banks and my bank FNB changed my debit orders. Vodacon excepted the change in debit order then never debited the new account. As this was a contract that already ran its course and the fact that didnt need the data. I paid no attention to it. The contact had gone month to month at R99pm for 2gig data. They have now listed me as over 150 days in arrears on the account(for which I haven’t received any data for the last 6 months on there and they say they are rightfully doing so and rejected Transunion’s request to take it off. You have no right to say it’s a contact agreement when the device was paid off over 2 years ago and the contract is for 2 years. Only serves as a reminder why I ported my phone away from them in 2008 already. This needs to be resolved