Mtn crocks people to get thier sales up

My Dad has had a contract with Mtn for over a year and a half I have been but am the user we have been paying R308 all this time so on the 15 November I got an suprising SMS I quote "Yello! You have started incurring cost from your Usage Limit. To check your balance dial *136*1*7851# or to manage your limit dial *136*5# Ts&Cs apply." I called the customer service asking them what is this I was told it's a limit that Mtn sets for all contract customers to my surprise the whole year and a half I was using this phone I have never received such an SMS I ask the consultant who gave them permission to to increase my limit cause no one informed me basically that's ***** I was told it was activated on the 23 of October 2018 by whom or why they do not know I specifically told them I do not want them to debit me a single cent cause I did not signup for that they told me this matter is escalated I will get a call from them regarding this matter this is the sms I got "Dear Customer, Your query has been escalated with reference number 1- ********** 9896. Thank you for using MTN. Have a Yello day" it's the first of December I have not received any response from Mtn ,my account was debited R508 when I call to get answers am being told people are not available Mtn is a ********** company now am being debited an amount I have never signed up for people must be aware of how Mtn crocks people to get there sales up.