Pathetic service - incorrectly billed.

I called the Vodacom cancellations department in November 2018, to cancel a data contract that I no longer needed. The agent (Mumsy) went through as much as possible in respect to keeping me on as a Vodacom customer and eventually called me back on the 19th of November, offering me a very sweet deal of R149.00 per month for a 10gig day and 10gig night surfer data package. I eventually agreed after all her persuasion and persistence. I duly received the modem and activated the package. I received the billing from Vodacom in January for R194.00 and this is where the problems started. I made numerous calls to the Customer care line, Upgrades department and have recorded names of all the people that I had spoken to but they refuse to acknowledge that the agent quoted me incorrectly and do not want to listen to the original recording. I even had a reference number for a solution expert yesterday, which they subsequently closed today, without resolution. I have called Vodacom every day from last week with confirmation that people are going to call me back.......no such luck. Today I spoke to Bongi who assured me that he spoke to Mumsy and she will listen to the recording and call me back......still waiting I did not want this contract, their consultants persuaded me to take it, so please just cancel my contract and collect the modem, so that we all can move on with our lives, or adjust the billing price to what was originally quoted .