STANDARD TRUST FRUSTRATIONS

I have experienced frustrations with Standard Bank's estate administration department called Standard Trust for over a year already. My mother passed on last year in July 2020. She had made a Will with Standard Trust. We as the beneficiaries lodged a claim with Standard Trust last year already, but have not been able to attain either credit agreements of the deceased or letter of executorship since then. We are taken from pillar to post without getting correspondence either telephonically or via email. What can be done to roll the wheels of Standard Trust under such an instance? Is there a body which we can report such ********* treatment? Your views and suggestions will be appreciated.