Feels like a Rip-Off

How does it make sense that due to a missed debit of R70 for ONE month due to misalignment of debit order dates, or Telkom debit going off later in the day than expected, the following month you all of a sudden owe R344.14???? Upon requesting to change the date it so happens that such a big company only has particular dates...which is fine but why charge so much if you know you cannot debit on certain dates that will align with everyones availability of funds???