Terrible Telkom!!!!!!!!!

I have a contract with Telkom Mobile/ Mando from March 2017 for a sim card with a certain amount of data and sms's etc for R99.00 p/m . When I agreed to the contract they told me that I can cancel at anytime with no extra costs. They started deducting R116.00 off p/m off my account. I left it there cause R17.00 isn't that much money extra, but then last month, October 2017, they deducted over R400.00 off my account and this month as well!! First of all I struggled to get hold of them and when I finally got to speak to an agent she promised me that the manager, Tonie/Jonie Venter, will phone me. A week after that and no phone call from the manager, I phoned again, more than ones, and every time its the same story, the manager will phone me, but she never does. I even had conversations with 2 different agents online on their website, but they were not helpful at all, the one even left the chat before I was done talking. Now my problem is, the numbers the lady Juliana Abriams, gave me when I agreed to the contract does not work, the number on the website, 081180 is occupied most of the time. Its always a problem getting hold of them. It is breach of contract for deducting more money off my account than what I agreed to and when I discuss it with one of the agents they just say if I cancel my contract I will need to pay a x amount until the contract is finished. I want to speak to someone to cancel my contract with Telkom Mobile/Mondo with no issues and no extra payment as Juliana Abriams promised!