Unwanted subscribtions to account.

So vodacom is allowing subscribtions to my account to whitch i do not consent. I lost so mich airtime already on 2 contracts because of subscribtions i dont even know is deducting R7 per day. How can this be allowed? Do i not even have the right to reject subscribtions? Because im never given a choice? Im told to just cancelle all subscribtions on a weekly basis if i dont want to loose airtime?