Complain against Absa bank

My father had an investment with Absa Bank then he passed away without a will. My siblings and I went to the Absa branch in Cofimvaba to access the money he invested but they advised that we need to have a letter of authority from court where we will select one of us to clam the investment which we did in December 2019 the 23rd, they also requested the letter of authority to be accompanied by my father's death certificate, his ID, the ID of the selected beneficiary and a proof of residence which we all submitted on the same day the 23rd of December 2019, the bank then advised we should deposit an amount of R500 for them to release the funds. We deposited the R500 on the 17th of February 2020 and and resubmitted the required documents as they advisedthey were not reflecting as received on their side then they advised that the funds will be available after 30 days from the 17th February. On the 17th of March when the money was supposed to be made available to us they said the required documents were not received again and that the letter of authority was supposed to have my father's bank account no. When we first went there they didn't say that the letter of authority needed to have my father's account no and the court advised that they only issue a letter of authority once, so now they can't issue us with another with my father's account number as they are saying now, the person who was assisting us every time we went to the bank is Sibabalwe who now has been transfered to Cape Town Absa, so now at Cofimvaba they say they can't assist us without a letter of authority that reflects my father's account no. Please help