False advertising by vodacom.

Vodacom called me offering me a deal(extra data) on my existing contract.before the lady could go on I said to NO I'm not interested I cnt afford to pay more than what I'm paying.she said no no you dnt have to pay anything extra is a promotion we giving for free to our existing customers.i said ok if I'm not paying anything is oky.come monthend thy debited R300 that I ddnt authorize.i called them requesting their call recording they said no is fine they will refund me.i waited nothing happened.called them again they told me is being cancelled and they opened a query about the refund.now today is the second month thy debited the same amount again.i feel ****** and frustrated.vodacom is not to be trusted it means this is what they do to millions of their clients without them knowing.