Standard bank disgraceful

Standard bank for some reason did not take off a debit last month on my loan account I have with them .I had to keep money in my account until the 9 th of February 2019 when my debit order was supposed to go off on the 25 th of January.I sent emails upon emails for the consultants to let me know what happened.Instead the consultants ask me to clarify security questions which is not applicable to me as I don't bank with Standard bank .When I responded to them to ask me a different set of security questions they don't reply .I have now used the funds in my account and will not accept responsibility for the missed debit order . Standard must explain to me why the debit order did not go off and not charge me the additional interest as a result of this ,failing in which a formal complaint will be lodged against standard bank and if there is no resolution it will be deferred to the banking Ombudsman.Standard bank please explain to me why my debit order did not go off in January,lest your offices is implying that I am no longer indebted to standard bank and my loan is written off .