Telesales promises

I received an offer from vodacom by telesales, for renewal contract I was not happy with the initial contract offered as my main expenditure was data charges then the gentleman promised an additional extra 2 gigs each month for free I clearly asked numerous times to make sure that what I was hearing was right, I have been to numerous vodacom stores to investigate none bothered. I then found a store while I was on leave that actually was willing to help and escalated the query to try solve it and I have had no feedback from head office . The 2 gigs that was promised by the sales man has never arrived since. The only extra data I received was the once off 10 gig promotion once signing a new contract. It seems the service provided in stores and telesales is merely about how many contracts a person can sign and not really about serving a customer instead. I have called, phoned different numbers no one can help?? I promise to fulfill my contract I would expect the same.