Subscription found

I do not understand.

How can my mother in law be subscribed to a mtn game thing when she has absolutely no idea how to do it?

My boyfriends and I have not touched her phone.

The sms told us that her subscription has been renewed successfully at R3 per day??? and we should dial *155#

So i did this to find out that she has been subscribed but how was this even possible?

I cancelled the subscription but this explains why her airtime disappears so quickly. Is there no consumer privacy and security?