Horrible service from Nedbank Chatsworth Centre

My dad had invested money with Nedbank in Chatsworth. He had recently passed away in January 2020, I had gone to the bank to arrange for my mum to receive my dads money as interest every month. I received lots of promises from Jaarfer and Zareena from the Nedbank Chatsworth branch. They have not kept to their word. They had given us the run around for my mums money. They took over a month to sort this out and knowing that my mum was old and unemployed, she is dependent on this money. The issue was only sorted out in March. Jaarfer had promised that he had my mums best interest at heart, to this date she is still experiencing problems. She has not received the interest for April, when I called Jaarfer at Nedbank, he gives excuses, he is using the lock down as an excuse... Nedbank is a big financial institute, being an essential service provider, I do not understand how lock down can be an issue. I do not know when my mum will stop having these issues with Nedbank, she is old, unemployed and has no other support. I need urgent assistance as I am not getting the help I require from Nedbank in Chatsworth.