Charged two debit orders by Telkom in one month

When my account fell due this month, a debit order of the amount due (R1091.00) left my bank account however I have been receiving constant messages from Telkom stating that my account is an arrears. I called the agent and offered a reference number of the debit order however she confirmed that the debit order did occur. The messages of my account being in arrears kept occurring despite the payment going through. On the 15 of July, Telkom took out an unauthorized debit order out of my account of R1200.93 which was on top of the R1091.00 they had already taken out of my account at the end of the account! How is it possible that I have been charged twice, with the second amount being a random amount that isn’t even owing!!!