Worst service provider

I updated my banking details with cell c in August and I was advised that my debit order will go off from my new bank account in September. In September my debit order ran from my old bank account. I called cell c to confirm that my new banking details were on their system and find out why it ran from my old bank account. My new banking details weren't captured on their system, so I gave them my new banking details again and I was advised my debit order will go off from that account in October. In October my debit order ran from my old bank account again, and bounced because of insufficient funds, because I am not using that bank account anymore. I called cell c to rerun the debit order as I had transferred money to my old account so the debit order would go through. They ran the debit order and it went through on my old bank account. I then gave them my new banking details again and was once again told that my debit order would run from my new account in November. In November it ran from my old bank account AGAIN. They also have not update the credit bureaus that I have paid for October, and my credit score is now showing I am in arrears. I called cell c to find out if the payment was reflecting for October and they advised me it was reflecting and I am not in arrears with them. I asked them to update the credit bureaus that I was not in arrears, and I was advised they would do that. Up until today they have still not updated my banking details, it has been 3 months, and they have still not updated the credit bureaus after a month. What else can I do ??