Dissatisfied with Vodacom service

I was assisted with an upgrade on 27.09.19 by Zwelli. He upgraded my contract to a higher value contract and assured me that no changes will be made to my existing contract other than the fact that he was adding 1 gig data more (because I was going to be paying more) to my 5 gig incentive data that was already part of my contract. So I was still going to receive minutes, sms, data and incentive data. This was on the Smart XS package. On 01.11.19, my contract was changed to the Uchoose Flexi with just R175 airtime, no minutes and sms. There was 10 gig data which said recurring. I phoned Vodacom and was told that my contract cannot be changed. I was then told that the 10 gig data was recurring for 24 months. On 01.12.19, my contract now just has R175 airtime with no data. This is not what I agreed to. How can Vodacom have a binding contract done over the phone and not deliver what is promised. Totally dissatisfied. I have called many times with no resolution.