MTN still debited my account, after I paid the amount

I had an unpaid debit order for the amount of December. I started getting SMSes from MTN saying that I need to pay the amount into the ABSA bank account urgently. I then paid this Money from my Nedbank account as an immediate payment on Friday 12 January and called the call centre so that they could pick up the payment and reactivate the services. I spoke to a consultant and confirmed the amount paid and he confirmed that he would activate the services. Which was done. To my horror this morning I get an SMS from the bank to confirm that MTN had debited my account again and that my account was in arrears. I called the MTN call centre again to clarify what was going on. I spoke to Agnes who confirmed that unfortunately a debit order request had been sent on the 13th and that they would not refund me any money as now the account is in the correct position. I am very mad because the SMSes I kept getting said pay the account, and nothing about a debit order that would need to be recollected. I don't understand this and even the explanation that Agnes made made no sense because she herself said that my account is paid in arrears so January's amount should be collected as per normal at the end of Jan/beginning of Feb. This needs to be rectified ASAP as the bank has given me a deadline of 15.00 to get my affairs in order. I need a refund for this as well as the charges for an account with a debit balance.