MTN TREATING ME UNFAIRLY AFTER ( TREATING ME LIKE TRASH)

I am disgusted by the service I am receiving from MTN. August is my last month of the contract, I called mid July to ask about the cancelation process and I was advised that my contract will expire in August and that I can only cancel once it had expired and the last debit had been taken. On my debit order date in August R1117 was debited from my account instead of R320 which is normally what they debit me. I reversed the R1117 and paid the R320 and went to find out from the branch and telephonically why they debited me so much and they advised that they had already loaded data on the 16th and that, that data was gonna cost me R797 because it was no longer on special but who agreed to that? Worse part is I called before my contract expired and was advised incorrectly about how I should cancel. Fine I advised that I will be pay that R797 end of September they just need to make sure that they don't load anymore data they are saying they can't access my profile before payment therefore data will be loaded again on the 16th of September what kind of service is that??????I WILL NEVER EVER AGAIN TAKE A PRODUCT WITH THIS SERVICE PROVIDER. YOU TREAT YOUR CUSTOMERS RIGHT ONLY WHEN YOU STILL WANT THEM TO CONTRACT WITH YOU AFTER THAT YOU TREAT US LIKE TRASH