Bank Charges for Unsucccesful debit orders

I took a contract with Cellc in may 2015. My payments were received every month there was no month when payment was not received. Whether by debit order or EFT or Cash payment. Yes I understand that a debit order is set up on my account but when my salary comes in you do not debit my account as agreed upon. Now please tell me although my payment was not always by debit order it was done by another payment method you still receive your funds. And if you have been charging me R70 per unsuccessful debit order even though you got payment. And this has been happening for the past few months why could no one inform me that I should not do EFT payments. Why leave it till my account is in arrears with a petty R41 do I get sms's to say my line will be suspended. Surely in some or other way your clients accounts and payments are monitored and if you can see I'm being charged fees that I could avoid you can inform me of that. Why let it continue or is this how you make your money??? I can understand if I ever missed a payment and never paid at all but this is not the case. Having a contract with you guys has been nothing but a struggle. And you will lose a client.