StandardBank NEGLIGENCE : I suffer consequences

I had an existing revolving credit loan and in Feb 2011 I requested for an increase of the loan to R120k. In July 2015 Standard Bank called me to advise that they deducted the incorrect amount from me for the last +- 5 years and that they have to increase the amount. I queried this matter with Standard bank and requested some sort of explanation of how this could happen and that why did it take 5 years to pick this error up. I did not get any sort of service and when I escalated the matter, the sales manager from Standard Bank Trade route called me in august 2015, to date she has not called me back. That same week I went into the branch hoping that I could get some assistance, this also did not happen. They advised me that they will get back to me and also to date no feedback. I then escalated the matter to the ecru@standardbank. Standard bank came back advising that I still owe over R100k and that if I am not happy I can escalate to the ombudsman. This decision is despite the fact the they knew about the incorrect debit order in 2013 and instead of notifying me of this they instead increased the loan amount without my consent and still left the debit order at the incorrect amount