Telkom - Incorrect billing since july 2023

I called into telkom to change my debit order date on 05 June 2023 to change it to the last day of the month and I was advised this has been changed, Telkom then debits my account 24 June 2023 and the debit order bounced, but I had made the arrangements with them, they tried to debit again 30 June and the money went off. 21 July they cut my line and I called in to ask why, i was informed i owe R168, i then made payment of R170, then end of August a debit order of 650 went off and my normal debit order amount is R449, 04 September 2023, they cut my line again and I called in to ask what is happening and now I am told that i owe R900 the lady who helped me says she does not know what to say, I have asked when I called in July to escalate the matter and I am told that the case is still open it's been more than a month and I am not assisted, they cut my line and debit money that was not agreed on, they did not change my debit order date and now i am the one in collections but i have paid up every month