MTN bills me extra on contract for bundles that are ****

Suddenly, three months ago (1st day of August), MTN started charging me more for my cellphone contract than they are allowed to. The contract is set at R499.00 and I have set the contract to not charge more than this amount by limiting it. Suddenly, MTN started charging R538.00 per month. This was not approved or required from me.

I called a costumer care agent and she told me that there is an added 150MB bundle on the account. I asked her to show me where I decided to add this. I have also sent an e-mail to the customer care centre and I have received a reply from Thobeka Maya but this person just stopped replying. I specifically won't do this as I use Afrihost for this every month when I need more data since MTN is too expensive for that. I need them to refund me for the months of August, September and October as well as cancelling this extra R39 for the remainder of the contract.