Negatively affected Credit score

I am really unhappy with the level of service received from vodacom. I had a contract with vodacom and decided to terminate it early due to financial constraints. I got in touch with their cancelations department and they sent through the quotation in which a payment was made to them. The lady I had spoken to said that the normal installment will go through for the month of December and that will be the final payment to Vodacom but the debit didn't go through. On the 13th of January I received an sms stating that an amount of R344.25 is owed to Vodacom and I immediately made a transfer but on the 15th a debit order went through from Vodacom. I got in touch with customer care and was told to wait 14 working days for a refund but nothing, I called again and nothing still. Today 07/02/2023 I checked my credit score and Vodacom is said to be in arrears with an amount of R1375 ayybo I was really angry and I called in only to be told its not their fault but the billing department will sort it out because on their side I am not in arrears my credit score has been affected negatively by this and vodacom does not seem to care.