Vodacom

I have a cellphone contract with Vodacom. Last week I got a phone call saying they want to lower my costs with more or less R50 per month, and I said that they can send me an email to state all the details so that I can have a look at what it includes and what will then be cancelled so that I can make an informed decision. After the call was ended I kept an eye on my emails, but I didn't receive anything. Later that day I received a sms stating they were busy with some process and then 5 days later I got an email stating they put me on a migration plan without me giving them permission to do so. End of the month I got a sms stating I will pay double the price of my original plan. When I called to ask to take me off the plan as I didn't give them permission they said they can change it back for end of December but I will have to pay for the month of November. This is unacceptable and I didn't approve anything, and especially not to pay double the amount that I'm currently paying!!