Disgusting service

I’m so disappointed with the service from Nedbank ,I have a student account which offers rewards ,I was given a voucher for unlock me rewards ,I got an sms saying I should confirm whether I will be choosing a Nandos Voucher or Shoprite voucher , I selected a shoprite voucher ,sms said that I should receive response with 7 days , I called the number provided aon the Ussd and even sent emails to the unlock me team however no one knows anything and everyone keeps sending me from pillar to post ,I went to the branch in Mall of Africa and the lady in the front end kindly insisted that I leave my details so she can follow up on Monday , I then received an sms with the voucher number ,I went to shop at checkers using the voucher however it says invalid ,I then went to a different store Shoprite ,still says voucher is invalid ,I tried again at Shoprite but the voucher is invalid ,I feel so humiliated standing in stores with an invalid voucher like I’m some ********* ,I feel so disrespected by Nedbank and I feel I unvalued,I’m so disgusted!