Std Bank Deceased Estate account in credit

My husband passed away 03.01.2016. I am executor to the estate. To date (18 Feb 2020) I am struggling to claim the balance of R1850 (+ interest) for an amount I was asked (by Std Bank, shortly after my husbands passing) to pay into our combined personal cheque account (apparently for an amount in debit, which was incorrect due to Std Bank clerical incompetence). The account was then in a credit balance and was to be refunded into the estate late account. Aug 2016 the estate late bank was closed in finalisation of the estate. As Std Bank now still had a credit balance on an account in the name of a deceased individual, it became my problem. 4 years later it is mind boggling that Std Bank still cannot underatand that the estate late bank account will never be reopened and that (if they bother to look) the transaction for the credit came from my Std Bank account into our then joint Std Bank account. I have email on email, one every year and some inbetween; numerous branch visits; uncountable telephone conversations (on my bill) to resolve this??? They have all the documents requested, confirmation of my account with Std Bank and the above story over and over and over again. If there is anyone at Std Bank competent enough to resolve this matter, please call me. If not could anyone please advise me who I could refer this matter to - perhaps Std Bank International office?