Incorrect Adverse Listing from MTN

I wrote a review on this page on the 02/05/2021 regarding MTN putting an adverse listing in my name on the 31/03/2021. No call/acknowledgement whatsoever from MTN regarding my issue. I called numerous times call centre agents saying I don't owe money as my number was moved to prepaid October 2020. I've requested a paid up later on numerous occasions which I have not received to date. I lodged a complaint with mtn and response I received was " we apologized for inconvenience caused please note that this amount has been written off". I rep**** and requested that they update the credit bureaus as they did when they put the adverse listing. This has not been done to date. I am dine begging MTN to do the right thing I need to escalate this. Hello Peter team, please help. Who is the telecommunications Ombudsman in South Africa, or should I just seek legal advice?