Greenbacks Redemption gone missing

I redeemed Nedbank Greenbacks for a Unit Trust Investment on 2 March 2020. I have made 5 (five) telephone calls mentioning to the agents that the transaction had taken place on my Greenbacks Rewards but that the investment had not taken place. I was promised by the last two people that I spoke to that they would call me back, the last person said that I would be phoned at a specific time, to advise the progress on tracing the transaction. I still have not received any feedback. This is the second time that I have to follow up on redemption of Greenbacks. This is a sorry state of affairs and I wonder how many other customers have been affected. This is certainly not a good reflection on Nedbank.