Website Payment Problems and Credit Damage

In Feb/Mar 2024, Cell C made an error in allocating payments I made through my contract profile on their website, and after 6 weeks of me calling several departments, they finally allocated the payments but I have recently seen that they have incorrectly flagged it as a late payment on my credit profile and have not bothered to correct it. And now after I made a payment of R2618.80 through my profile on THEIR website, today on the 22nd of September it still shows as an outstanding amount against my account. I am already anxious because I am going to have to go through the same long process of explaining to them how they need to fix their issue. I am also very disappointed to see that they did not correct the false information on my credit profile and I am looking to escalate it to the ombudsman.