MTN prepaid per minute rates

I just want to know if the man on the street knows when MTN gives you a Wow bonus they charge R3 per minute and R5 per minute between 7am to 9am and than the consultant say proudly the TC is on the MTN App, my question to her is what if you don't have the app her reply was if you enquire or call the customer helpline they will tell you. Is there somebody where we can complain about the way in which MTN is charging their customer's