Nedbank false adverti*****t of monthly cashback when you successful transact a loan repayment via debit order

Nedbank offerred me a cashback monthly should I open an account with them and successfully transact my debit order. Three debit orders have gone off and only one caahback has been received. I was only paid the one cashback after I had to constantly follow up and escalate this to their complaints department. Shevlin Constance the Client Manager handled my complaint last month and assured me that it would be automatically allocated at the end of each month. To my surprise, I still await the 2nd cashback and the same Client Manager is now not able to respond to what happened to it will be automatically allocated. It seems as if they are least bothered as I enquired about this beginning of January and till date nothing has happened.