Services of Telkom Sucks Bigtime

I canceled my wife's mobile contract with Telkom 2 years ago. When starting the process of canceling the contract the call center agent notified me that I still have to pay one installment which they debited from my account the following month. But after that, they still debited the installment from my bank account. I stopped the debit order so that they no further deduct any money from my account. I received an email from them stating that they will hand over the "account" with an "outstanding" amount of R400.00. I accidentally made a payment for the amount of R700.00 on the 10th of September 2020 to stop them from harassing me. But still, they did not recognize the amount of R700.00 after sending them the proof of payment on several occasions. A month ago their lawyers phoned me and instructed me to pay R1205.40. I did explain the matter to them and also provide them with the proof of payment. But they still carry on phoning me.