UNAUTHORISED DEBIT DEDUCTION

My bank account has been debited for my home loan account on the 15th of January whereas my debit order is for the 25th of every month.I have called standard bank as soon as the debit went off. They have informed that there was an error on their system and i am not the only one who this has happened to. They have promised me to refund me. Up until today, a week later I have still not been refunded. When I called yesterday they told the refund has been done. Today when I called they told me I must go to my bank and have it reversed. I bet another debit is going to come off on the 25th again.What gets to me is how they ****, telling me that they will refund me, then telling that they have already done the refund. In the meantime they have done nothing. Now they expect me to go to my bank and have it reversed, whose mistake was this? Why are you inconveniencing me? REALLY PATHETIC, INCOMPETANT $*@^$@!