Customer service and complaint department issues

An amount has appeared as “reserved” on my account for more than two months, even though the authorisation department has confirmed that it is not reserved. No one can explain what this amount relates to, nor from which date this transaction has been pending. I logged a complaint last week Saturday, but ABSA seems unable to understand the issue. Despite multiple telephone calls and emails, I have received no resolution—only repeated promises that a manager would call me back. Unfortunately, that has not happened. ABSA can see the amount, yet no one has access to it. Not even the ***** department could assist me. What steps can I take next to resolve this problem?