Cell C data

Some time last week I received a call from Cell C rep, she offered me 100GB of data for R199.00 as she said they have black Friday special. The offer was accepted and concluded and she said the data will be loaded on my Cell C number but that never happened and they will bill me on the 20th for the data that they never load. Cell C customer care was contacted and they kept moving me from pillar to post and never assisted me, now I called again yesterday to cancel the offer because they didn't load the data as per our agreement and they never helped me and now I will pay for data that was not loaded on my sim card and Cell C does not want to help me nor cancel the offer they keep on transferring my call to other departments with no luck.