Changing debit DATES orders without my permission

Changing debit orders without my permission???? I actually received no SMS about early payment/debit order. I got a statement today and saw they tried to debit on the 21st, I did not have enough money in account so obviously it did not go off. My debit order is set for 26th as I only get paid on the 25th of each month. Now they want me to pay a debit order fee of R70. Imagine they doing this to all clients and 1000's are getting paid normally so they score R70pp that did not have money in their account. I have been a loyal customer for a year now, no debit order problems but this I will not accept. Tried to call the call center and all they said was sorry mam, but there is nothing I can do this was a once off thing that happens. Unacceptable Cell C! Really some bull**** you are busy with!! R70 is not a lot of money in todays time but can be a HUGO PAYDAY for you as a company!!!! No, fix this!