CellC lies to customer re contract conditions

I called CellC on the 28th of March 2016 to ask about an upgrade. I was on the Discovery Vitality 400 plan. I was told I could ugrade to Pinnacle1000 where I will get 1000 minutes, 1000 SMSs and 2GB of data per month for R1149. I thought it was a good offer and accepted over the phone. However I noticed that I only get R1000 per month which covers calls, data and SMSs. That was not the deal I signed up for. I called on 5 April and was given a reference number #***. Agent JHB6138 promised to trace the call and get back to me within 2 days. I spoke to Miriam today and nothing has happened yet. CellC cannot do this to me as they are offering me conditions for which I have not agreed to or signed up for. According to contract law they cannot change the conditions of an agreement without my consent or informing me of the change to which I have to agree. CellC you have until COB today to respond to me otherwise I will report you to the Ombudsman.