Debit order bounce fee

I'm not happy with Cell C at all. In this tough economy cellc charges its clients what they call a debit order bouncing Fee. When my debit order to them returned I didn't want to miss a payment so I took the liberty to make an EFT payment because from past experience I know if no payment is received they go as far as block your line and even have the audacity to charge a "bouncing fee"

So yesterday I phoned them to inform them that my banking details have changed and request that they move my debit order to my new bank. I was told it's not possible because any financial changes need to be communicated 30 days prior. It's funny how none of this is told to you when you take up a contract with them. So the gentleman further advised me that they will still debit my old account and if the debit order returns they will charge another bouncing fee. How fair is this to me as a client. I have two contracts so they will charge me R70*2 even though I have notified them of my change in banking details.

Cell c is a ******* I must say. I need someone at cell c to give me a solution to this problem because I can't keep paying bouncing fees.