disapointment and bad servise STDBANK

I have a bond account with STDBANK, which on Dec2014 I made early arrangement for my debit order to run on the 15th and January to be back on the normal date the 20th, and yesterday I realized from statement that they debited me on the 15th and they even have a nerve of calling me telling me I'm in arrears, and when I check January too they did the same thing in debiting me on the 15th and on the 20th too, and I spoke with the supervisor by the name of Mark yesterday who could not even pick up from their records that they debited me twice for January and I sent him my bank statement as a proof which he did not even bother to sent me an acknowledgment of my email nor dealt with the matter. today again I have been harassed again with the same thing that I address with them and no one at STDBANK who have the decency in resolving this matter the team leader and their consultant are throwing me from pillar to post with the fault on their side but good at harassing me. Such a big bank do not have records of my call I made on Dec arranging this I confirmed with Thembi the consultant who said their team leaders are not available and they will call me in 20minutes which has past.