Messing up my credit profile

I had such a terrible service from Standard Bank life. Last year I took up a life policy with Standard bank and made it clear that I want them to debit me on the last day of the month. I normally get paid on the last day of the month and they continuously keep on visiting my account any day they want to and that messed up my credit record as the debit order was returned due to lack of funds. I want Standard Bank to take responsibility for this mess on my cheque account. They attempted to debit me on the 28th January 2015 and their debit order was returned as only get paid at the end of month. I'm so frustrated because that move messed up my bank profile. If Standard bank isn't taking any responsibility and reimbursing me all the charges incurred when their debit order was returned, I'll be left with no choice but close my policy with them and look elsewhere for life cover. It is a day light *******. If the scenario was that they attempted to debit my account at the agreed date and there was no money in my account, then I'll take full responsibility. I'm so disgusted on how Standard bank does its business. I can only imagine what happens to illiterate customers!