Not received my promotional 30 gig after 6 weeks

I bought an iphone 6 (LTE device) on contact at MTN Wonderboom Junction and it was activated on 12 March 2016. The promotional offer was that you receive 30 gig data free for a month if you subscribe. When I still had not received it by 15 March, I contacted the store again and they advised me that they would log a query as it was not an unusual occurence. The reference number I received was ***. A week later nothing had happened. I then phoned customer care on 808. Reference number was ***. The consultant told me he would escalate the query. Still nothing happened. I called customer care again a few days later and now they said they could not do anything as the store I bought it from must load the 30 gig. So I called the store again. I spoke to Uddi numerous times (calling on average twice a week) to ask for the 30 gig. She also said she would escalate the query. Up to date nothing has happened. I have now been using the phone for nearly 6 weeks. I get no feedback and I still do not have my 30 gig. I really do not know what to do next.