Taken for a ride

since January 2020 I have been calling Vodacom Call Centre regarding the data they are loading for me every month. I told them that i don't need data they should cancel it but it seems like they don't want to listen to me. When i signed up with them i told them that i only need airtime based on my budget I knew that i can afford to pay R420 every month. Now to my suprise i am paying different amounts every month like R700 and R600 and something which i didn't signed for. Yesterday i called the call centre to double check if everything was in order and if they did cancel the data issue and i was told that they did. but to my suprise again i received both airtime and data. what should i do? I think people are trying to take advantage and that's why i ended up installing a call recorder on my phone to record each and every call that i make because i have been taken for a ride. If this is not sorted I will be taking further. Someone needs to call me with a solution.