Vodacom is cheating me...

I'm totally furious with the level of negligence I am forced to deal with from owning a contract. I have 3 contracts one of which in question I took out the sim card to use another prepaid and have been paying a fixed amount. Until last week I got a notification about an unusually high usage of data. I immediately called to enquire only to be told my number was active even as I was calling and heavy data usage was being detected. I requested they block it and detect as much info about it but it was unsuccessful. Since then I have called all vodacom helplines and been to Maponya, Centurion and Vodaworld with unfruitful results and being sent from pillar to post. Meanwhile the deduction will inevitably go off tomorrow and I'm supposed to sit back as helpless because no one so far has helped me. I'm sick and tired of being cheated like this and will retaliate in any possible way to have this nonsense resolved.