Premiums deducted not as per agreement

On the 18 January I received a message to say my contract has ended. An hour later I received a call from a MTN consultant offering me data deal of R100. I informed the consultant that I don't want to continue with the contract and would rather have it cancelled. After chatting for a while regarding the data deal she was offering , I accepted the offer and asked if that is the only money that I will be paying since the actual contract ended. She assured me that the only money that will be deducted from my account would be the R100. I asked her several times to confirm that as I knew that I cannot afford to pay anything more than that, and she assured me that R100 will be the only money I will pay and not the previous contract amount. The consultant informed me that if I cancel my contract, MTN will deactivate my number, and that is the only reason I agreed to take on the R100 data plan. She might have BS'd me and I fell for it. Now end of Jan, Feb and March 2023 I noticed that the same premium I was paying for the initial contract that ended is still being deducted and not the data plan R100 only premium. I tried to contact the call center and I kept being put on hold with no assistance.

I demand a refund for the 3 months premiums deducted from my account.