Terrible Customer Service

I must say I am quite disappointed. I took up a cellphone contract end of July with MTN at the Maponya Mall branch in Soweto and the service I got there must have been the first red flag. However that is not the reason for my review. When I took up the contact I was advised of the deduction dates they have an unfortunately was advised there is no deduction date of the 27th which is my salary deposit date so I had to settle for the last day of the month. I receive an invoice at the beginning of every month outlining my payment for that month and the payment options. So for the month of September I decided that I cannot wait for the 30th because I have too many financial commitments and I do not want the payment of my contract to be affected, so I decided to use the payment options on my invoice. I paid using Scan to pay... I scanned the QR code on the invoice and the payment went through. I then called MTN Customer Service to check if the payment was received and to ensure that no debit order will go off on the 30th. The lady I spoke to told me that I was not supposed to make a manual payment. I asked her, you guys send the invoices with the payment options at the beginning of the month, so if mid month I have enough funds to pay the contract and want to pay using the payment options on the invoice, I am not allowed to do that and she said yes, because that is how "our system" works. So now tell me why does MTN send payment options if we are not allowed to pay on any other date besides the deduction date? Where on the invoice does it notify the client that we are not allowed to use the payment options? Where on the invoice does it say that if we make manual payments we will still be liable for payment on the deduction date? I am a young lady trying to build a credit profile and I want nothing to affect my payments which is why I even took it upon myself to pay before the deduction date and what did I get in return? A customer service consultant telling me I should not have done that. No empathy, no consideration, no willingness to help find a solution, just generic answers. The energy I got was "you made the mistake, you must see to finish". So I need to ensure that I have funds in my account to avoid a missed debit so it does not mess up my credit profile and wait 7 to 14 working days for a refund or if I can't come up with the money, let the debit order bounce and deal with the consequences. I work in customer service for an insurance company and I must say being on the other side of the phone is so different. You can hear that a person actually does not care, they are there to do a job. All I can say is... Try somewhere else.