Unfair marketing

Dstv called me and told me they will upgrade my decoder to a dstv ultra decoder, which when they came to install they put in the incorrect decoder, when I called , I got sorry that's what you qualified for but that's not what we agreed on the phone call wich I know all calls are recorded, they said they will collect the decoder, they haven't, it's been over 3 months now ,nothing from them I've been literally calling every 2nd day , only to be told we will escalate your call , but no1 has called , what you doing is against the consumer act prohibit "certain unfair marketing and business practice" I even decided to go to multichoice myself and they said I will be called after 7 days , still waiting, so feedup and disappointed