Unhappy with Cell C service

I bought a contract phone from Cell C in October for R509 on elevator special and was promised a free 30 gig on my plan, the first data and airtime was loaded on the 20th October, the 30 gig was not included. I am on my 3rd month and I have never received the free 30gig. I called to inquire on the 1st of January this year and was promised a call back in the next day or two up until today I am still for the call back and I also haven't received the 30 gig