Migrated by Vodacom to an unwanted, not requested expensive package

I phoned Vodacom and asked how to add more minutes to my Smart S contract. They told me they would change it to a Top up Smart S and I could then just buy minutes through my bank and add them on. The cost would be about R3 more than before, they said. Well... I just got charged a whole lot more. In March they took off R1014 which is WAY HIGHER than before.. I went to A Voda4U shop at Rand park Ridge who showed me that I had been migrated to a Smart Top up S contract with 650 MB data (which I didn't ask for - I have Wi-Fi all the time) and all I wanted was to add more minutes. And it costs a whole lot more. I am a pensioner with virtually no income and I simply cannot afford this package WHICH I DID NOT ASK FOR. Listen to the recording of my call. Show me where I signed for this increased cost. I want to be put back to exactly where I was before this unwanted migration without any more charges). Please HELP!