Dragging out response from call centre

I received my Cell C bill at the end of August, only to find a R 2780-00 amount deducted off this account. My account on this particular contract has never exceeded R 200-00. For the past few months we hardly use this account, as we now have wi-fi at home. <br> I phoned the call centre to try and sort this out two weeks ago. Firstly the call centre said I would need to have a look at the itemised billing and validate these calls. The first thing that stood out for me was the fact that there were phone calls on this account. This completely surprised me, as the dual sims are in an iPad and ****le respectively. We do not make calls off this account. <br> I then phone the call centre back to formally log a case. They said that they would get back to me within 48 hours. I phoned back three days later to follow up. They then said that the calls were validated and there was nothing that could be done. I refused to accept this, I was then told that Technical will have to deal with this and would get back to me in 48 hours. Three days later I phoned to follow up. Again i was told that the calls were validated. I refused again and then they said that someone would get back to me..still waiting!!