Netstar deducted an amount that was not agreed up

In October 2015 a has a call from an agent marketing their product.we then agreed on R 120.00 for monthly premiums. In November a debit of R 240 which was not the amount agreed upon. I then called the agent complaining about the amount deducted. They said they will look in to it. To my surprise again in December they deducted R 193:00. And they did the same again January and decided to reverse the payment because no one fixed this for me. InFebruary they still deducted R193 and reversed the payment.again.I decided to call and spoke to a agent called Neo Nkabi. He then referred me to a lady called Cecelia but she was not available. I called again in March and transfered to accounts where no one picked up their phones. I tried again and spoke to fanyanaand needed him to assist with ending this contract. I was transfered to another person and she was rude and said that I will have to pay a penalty of R 1000. But still refused to close my account with them. I also received an SMS saying that I will be liable for R 8000 if I don't get my account up to date. This I very confusing to me because I agreed to R 120 and none of that has happed and the last agent was very rude to me.