Nedbank cash back is a lie

Nedbank promises to give you cash bank of R200 on a monthly bases if you open an account with them and deposit at least R4500. It's been 2 months now I have now received anything and they send smses with invalid reasons as to why they didn't stick to the agreement. I tried calling customer service number they said they'll get back to me, until to day still no word from them. Don'take promises to clients that are not adhered to.