Cell C theft

I have three Cell C contracts and made it my business to get all my friends and family to join the Cell C family. I upgraded one of my contracts in December. Then last month I received a invoice for R300 more than the amount should be. I contacted Cell C and they informed me that I have data free for 3 months and that the three months had passed and I now had to pay for the data. I did not know about this data untill I received this invoice. I do not need data as I have a MTN contract with 20GB. I asked why nobody contacted me to say that the free deal has passed and I now need to pay for the data. The lady said they will get back to me. I then (after I contacted them for the first time) received a sms stating that I now will have to pay for the data as the free data expired. I contacted them again and explained the whole thing again and again they said they will get back to me. Till now nobody contacted me and the debit order went through. I feel that that is theft. I feel that they were supposed to let me know about the data and ask me if I still wanted it. 2 GB for R300 when I get 20GB for R169 from MTN.