**** service from MTN top up contract

I have a top up contract with MTN. when i get my statement this month its almost R200 higher than my normal monthly payment. When i query the amount i am told they send sms's to customers in september telling them they are increasing their limits. And you must respond yes/no if you didnt respond its automated "YES" i mean what nonsense is this. How do they even know you got the sms in the first place.

I mean if i wanted my top up amount increase i would have initiated this not them. I am the one paying this contract some fool can not just wake and decide I need my limit increased.

MTN better sort this nonsense out I am not paying that money I never agreed to it in the first place. I want this sorted out.