Unfair Billing by Vodacom

I bought a Lenovo Laptop which was for 24 months in contract and It was meant to come to an end in May 2019 if am not mistaken. My monthly bill was sent to my alternative cellphone number as an MMS I provided the service provider, which was never a problem until came the month my contract was coming to an end of 24 months. I was not informed through my normal billing number which was my cellphone but instead a SMS was sent to my data Sim card (I was told) that I received with the Laptop which was on a router nor was I called to be informed about the procedure of terminating the contract as I had thought it will automatically cut off once the 24 months were over but that was never a case. I had been on errears so one day I made a call to get a settlement amount for the months I was behind with, instead I get informed that I was still being charged for without my knowledge. I feel I was unfairly billed and the normal billing procedure was neglected to inform me on time to do the relevent procedure to terminate the contract and had put me and my name in unfavourable position financially as I have been handed over for something that could have been avoided.