Very bad service by telkom agent and incorrect billing

I have a contract with Telkom, I went to their stores to tell them I've changed my banking details and asked me to send the the proof of new account. I did that and they came back to say they do not accept Discovery Bank so I should make a manual payment. On the 20th of Feb 2021 I did that because I knew there won't be funds on my old account as it is no longer working. To my surprise today they sending me an invoice charging me R202 for the bounced debit order and funny enough on the statement it shows my manual payment so clearly someone from the accounts department should see that the money was paid before the 25th. I called their call center and after holding for over 10 minutes I got hold of someone by the name of Pamela who was very rude to me. She was not polite at all, in fact rude as she was banging the table while talking to me because I didn't want to accept paying a charge for something that I have already asked for. I asked to speak to her supervisor or manager and she told she is working from home and have to ask her supervisor to call me back, a shock of my life she put me on hold for like 5 minuets or so and when I asked why she did because I am using my cellphone and airtime for this call and she told me next I should use a telkom line so that I don't complain about my airtime when I tried to answer that she dropped the line on me. I am so angry and wish to cancel the contract even, I've been a very loyal customer never missed a single payment instead I pay my account early or in advance sometimes for me to be treated like this by Pamela. Your calls are recorded so please go and listen to that call.