Billing frustration and Poor Service

I took out a contract with Vodacom in 27/02/2017 everything was going well until December 2018 where my bill changed drastically and I enquired through costumer service where I was told that is because I upgraded at some Vodashop in Cape Town. Which I didn't takeout any upgrade I then opened a case of ***** as I was advised and send through the necessary documents to ********** Which I received an SMS confirming ********** after few days but the bill was not resolved. I then called costumer care again received a ref no. 1- ********** ********** but seeing that the matter is not being resolved I decided to visit Vodaworld in Midrand on the 4th of January 2019 where I was assisted by a Lady by the name of Mulalo Mutau which she told me that she logged the matter but even to this day there is a huge amount on my account and on the 28th January 2019 I called this number ********** to give notice for cancellation but I was told I've been migrated therefore I can't cancel my contract. So i'm just tired with Vodacom and their poor service never again will I takeout a contract with Vodacom nor would I recommend it after this poor service I've received.