double payment

I upgraded 2015/07/03 at the MTN Branch in the Kolonade Centre in Montana, Pretoria. I was assisted by the manager of that branch and on this day she informed me that my debit order that was supposed to go through on 2015/06/26 did not go through so I had to pay that amount that did not go through as well as the amount for the next month meaning the amount due on 2015/07/26, otherwise the system would stop the upgrade and the upgrade would not go through. I did pay the amount of R 2820 at the ABSA ATM,and the upgrade was completed.Last week I received a statement that I owe the amount of R 1731.71 (I already paid for the next month) I went to the North Park branch this morning and the informed me that on the date of upgrade I had been 2 months (May 2015 & June 2015) behind on my accounts payment which is not true because I have bank statements and \notify me's"from my bank proofing that all payments before 26 June 2015 went through."""