Outstanding credit of deceased account

My dad (P. A. Willemse) passed away 0n 22 May 2022. To close his account we had to deposit an amount of R1400.00. The lady at the bank informed us that there is a credit of R700.30. We provided them with all the necessary documentation which was needed on May 2023. And again in October 2023. We followed up with Standard Bank Sasolburg, a couple of times since then, without any success. I need to put this behind me and carry on with my life and I am fed up with all their lame excuses. They must pay out the interest on this amount is as well. J.P. Gloy