Mtn messed up my bank account

I canceled my debit order with mtn on the phone and I was assured my debit order was canceled I can start paying on manual in end April 2020. End May, they tried to debit and not get anything from my account and it charged me R147.00 During May 2020 I received a call from mtn on top ups in my account on data, then I asked them if the debit order was canceled they said yes. I rejected the data offer as I got WiFi at home. I missed my June 2020 payment, which on the 28th of June 2020 I personally went to Mtn to make the June and July payment, which I managed to pay and close the arrears. I had to ask the guy who assisted me if my debit order was really canceled he said yes. June 30th 2020, a debit order bounced back from Mtn, leaving a charge of R147.00 after I was assured that I’m now paying manually which I even paid for the new month of July. July 1st , another debit order bounced back, leaving a charge of R147. Now I’m not happy with that because those charges now amounts to R441.00 if charges from my bank account, for no reason. I went back to the store yesterday and they told me that they can’t access my account and I should call 135..The treatment I received from mtn is extremely appalling ..I would like to have my back charges refunded..can someone from mtn please call me to sort this mess out..