Registered for MTN services without my consent - lots of airtime down the drain

I am an MTN pay-as-you-go user. I recently received an sms from MTN stating that my "Subscription Service to MTN Gamer+ at R 3.03/day was successfully renewed.". Somehow MTN registered me for this service. I certainly did not register for it myself! I now know where my airtime had gone these past few weeks.

It is really upsetting to know that MTN can somehow register me for services and then subtract my airtime everyday without me ever giving consent.