MTN *****ing money out of my bank account

Dear MTN,

I would just like to find out how you figure it is legal to deduct money from my bank account that I did not sign for?

I received a spam SMS that stated: Welcome to Lalamobi. Cost: R7/day. To unsubscribe SMS stop to 31789. For help dial ********** 472.

I rep**** with a 'STOP', and received a SMS stating: 'You have been unsubscribed from Lalamobi 31789.

But a month later I get the same SMS saying Welcome.

NOW... the thing that bothers me, is that I have a fixed data contract only! I signed for a certain amount per month, and even stated to limit my over-usage to R0.00. I received my MTN invoice and to my surprise, I am liable to pay more than what I signed up for.

This is theft! If I do not get my money back, I will cancel and close my account with immediate affect!!!