NEDBANK does not pay out deceased estate money

My mother past away on 05/04/2017. Me and my brother went to Nedbank with her death certificate. They told us that there was no accounts in her name. A few months later the executor went again and again they said that she closed all her accounts with them. Then in Febuary 2019 they tried to contact my mother to sign documents for her investment with them. Only then did we discover that she had a check account with money in it at Nedbank and also an investment of a few R100k. We have been struggling since then to get the money from Nedbank into the estate account. Last week the check account money was transferred but the investment are still not paid out and NOBODY at the branch are helping us. This is the reason that I will never bank with Nedbank.