Standard Bank removes revolving credit abiliity due to their own inability to take funds as per mandate agreements

Standard Bank continuously deducted my revolving credit amount before my monthly salary was paid into my account leaving me with additional bank costs to honor 'other amounts' that would have gone off successfully had they not taken their premium prematurely. On insisting that they change their debit order deduction to the 1st of the month to avoid further unnecessary costs, I was told I was now in arrears and my funds frozen (even after I settled the amount they claimed I was in arrears with. Their service is always less than adequate and seems thats what they stand by.