Mtn is treating customers unfairly

I have been treat bad by mtn and it's consultant every month, siziphiwe matshangana she told me she will terminate my call with giving clarification why they debited so much money on my account. I'm suppose to pay 224 rands for my two contract phones but they debited 582 rands from my account which is for me it's unfair and misleading because they said me an SMS stating that on the 28 of February 2018 i wl pay 224 but when it comes the I must pay they take so much money and they want me to pay in cash