Being Charged for Failed Debit order for A Date I did not select.

When I signed up for my month to month contract with Telkom my chosen debit date was the 15 each month, debicheck on my banking app proves this. Telkom has never debited on the 15th. Instead I would end up going to pay my account cash at Woolworths due to being worried about arrears. Contract was due to end June 2023. Suddenly Feb 2023 they start trying to debit on 5th of each month. I continue to pay Cash at Woolworths. March 2023 I get a debit rejection fee for failed debit. I call to dispute it was resolved. APRIL 2023 Same thing. I call to dispute. Meanwhile I continue to pay cash. May 2023 Again. I had it and decided to cancel contract. Telkom insists on debiting 5th of every month. Every time I dispute I ask the agent to change my debit date to 15 or 30th. They say they have. Still nothing. Last payment was due 05th June 2023. I pay at Woolworths on 31 May. Now waiting for Final Statement with O balance. Nothing. June nothing, July nothing. August boom I get a message that I owe R202. Ignore cz obviously its a mistake. For the first time ever on 15 August Telkom debits the R202. I dispute on cellphone app and reverse. I cancel debit order as well. Called Telkom same day. Lady at call centre says the R202 was for failed debit order in June 2023. What for? Contract was cancelled and paid up. The money reflected after they tried to debit on third side but is showing I paid on May 31. She says she will open a dispute log for me, it will be resolved within 72 hours and I will receive my final statement. Then boom August 25 2023 I get email from Telkom lawyers that I owe and must payup or I will be taken to court. For what? A failed debit order for the 5th. Who said debit on the fifth Telkom? You chose your own date and now penalise me for it? The account is not even going unpaid. Telkom is the worst I will never forget.