Mtn Extra time *******!

Mtn they are *****ing my money with EXTRA TIME thing. After I realized that my airtime is disappearing soon after I recharged it, I then decided not to use that sim card for a while because I had another sim card. Then two weeks ago I then bought airtime and recharged the sim card again. To my surprise when I checked my airtime balance I was left with only R0,00 from R50. Then I got the message saying I still have to pay R13,00 for Extra time bundles of which I know nothing about it. And I don't remember activating things like that. Now I called Mtn they gave me this number *136*774*3# to cancel it. I did canceled it but now it seems like Mtn they are using this Extra time thing to ***** people's money because yesterday I recharged the same sim card. Today when I checked my airtime balance it showed that I have R11,01 Data 250 Mb and Minutes 60.00 So please MTN I don't want anything to do with this thing called Extra Time. Mtn take that data and minutes of yours or else I will just stop using your network. Please stop *****ing from me because I can buy myself airtime and data. This is the third time you Mtn taking my last hard earned money. I wat my money back tjerrrr.