Telkom sucks!

Having cancelled my fibre to the home contract in August 2020 and having paid the call charges in full and the rental charges pro-rata to 29 September 2020, Telkom sent me an invoice for the balance and charged interest on "late payment". I then called them and spoke to a consultant who advised that they will pass a credit for the outstanding amount of R194.03. However, I have had a default listed with Experian which has affected my credit rating. I am now unable to get through to their billing section to discuss the matter. There is supposed to be an option 4 to select to speak to a consultant, but guess what - no option 4 !! This is one of the reasons why I cancelled my service with them. How can I get this debit reversed and my credit rating fixed if I cannot even get through to them? Whatever you do, do not do business with Telkom!