Vodacom *******ly changed my contract

I signed a contract with Vodacom a couple of years ago and when the contract expired I continued on it. A few months ago I got a call about upgrading my current contract with Vodacom. The new deal would give me slightly more data and voice at a slightly lower monthly price. But when the first invoice came it showed something completely different. I am now paying more than I used to. I have contacted Vodacom call center regarding this problem and after an hour and a half on the phone with them they said they will get the recording of the telephonic contract and come back to me in two weeks. It has now been three weeks and still nothing from them. I guess I can assume they will not get back to me.