MTN ~ Not a Happy Chappy

Can some please explain to me how MTN allows for certain deductions to take place on a contract that you did not ask for or sign for. I receive a certain amount of data and minutes and airtime each month for a certain figure, all was well at the start. But lately there a few random deductions coming off from my airtime & data every month, so much so that it leaves me to go buy additional where I never use to. I called MTN, not very educated in response, as all they said was "I must have clicked yes on an SMS." Firstly that response is poor, and shows zero customer value and support. I don't need to be told that I must have clicked on something. This is absurd and not the response one should pass to a loyal customer for years, and nor does it fix anything. I did not click anything, in fact I avoid all risky looking messages these days due to the high ***** activities.

Point of the matter; I signed for this, expecting and paying for what I signed for, but not getting what I signed for initially. Why is there NO control over customers billing and how can just anyone take funds from a contract account so easily without my knowing???