Nedbank salary switch benefit not honored

Nedbank promised me a 500 Cash back for opening my account and switching my salary to them which i did, from march till date my salary is paid into the migoals account, however i have logged a complain for that cash back and was told to wait 21 days , its been more than 21 days and when i do a follow up , no one is responding to my emails now, this is not the service i had in mind when decide to accept an offer to reopen this account , but how my query has been handled is so unprofessional and really make me wonder if this is how they treat us their clients.

Please can i get when is that money going to be in my account, ad whatever investigation should be done they had enough time to do then. My email adress : Maremahaec***mail.com