Debit order Mess

I have recently got Mobile and Data contracts from Telkom. Due to unforeseen expences my debit order did not go off, but paid it before the month ended. Then they took 2 Debit order amounts. After several phone calls I still do not have any answers. According to me they owe me one months debit order amount, but I still receive SMS's stating that I owe them, and my service will be suspended if I do not pay.