Change of contract without my knowledge

I have a contract with MTN that I signed for on the 15/06/2018 for an Apple phone 7 32GB under MTN Made for me S @349. I added data package which made it to be R549 of which it ran smooth for months.

Last month all of a sudden my Debit was R 2032,99 and I logged a complaint and today I was told that the extra charges was a Pro-rata charges because my contract was on special for 24 month so now since it has expired they are charging standard fee. The reference number I was given for my complaint is ***

1. When I signed for this contract it was never stipulated to me that after 24 month it will change.

2. How do they charge a Prorata that big whilst my contract is in its 24th month and I never even cancelled or did anything to it?

3. I've checked the original contract copies and there in no where were it has that stipulation.

Kindly attend to this problem because I cannot be paying so much for Apple 7 (4× my original debit) because since I have been pushed from pillar to post, I am left with no choice but to lay a complaint with the ombudsman and legal services.

Mr PS Tshabalala

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