Billed wrong and no response from the service provider after visiting the store & making two calls

On the 14th of September 2017 I was called by Bradley Marian from MTN Direct in their sales department. The call was about my cellphone contract upgrade, which on the same day he sent me an email. I told Bradley that I do not want a device as my device is still in a good condition. He then offered me a package of 100 minutes, 100 sms and 3GB data for R199 (he said if I need a device at a later stage I must contact him directly), which was confirmed telephonic. I receive my statement and the amount is R359. I then send Bradley an email on the 22nd of November 2017 and I did not receive response from him. Yesterday I go into an MTN store in Glen Marais (an area in Kempton Park). They tell me that they cannot assist me I must call Mtn Direct directly. I call Mtn Direct's customer service and I speak to Mapule but she cannot assists me further. She asks me to drop the call and call back as she cannot transfer my call to the sales department. I then call back and I speak to Rashkee. She says the reason why my account is R359 is that I still have my insurance on the device I an currently using and the 1GB data which I added to my previous contract. What I do not understand is that the additional amount I am paying with my current upgrade is R166 and that the insurance and 1GB data was taken with my previous 24 months contract with Mtn. The amounts do not add up for insurance and the 1GB data. How is it possible that they can add it to my current upgrade if I did not ask them to add it. Which Bradley did say that he will ask Mtn insurance to call me so that we can discuss the new amount of the insurance for my device. The other thing is of the 1GB data which I added to my previous contract is still continuing without me knowing, I should be receiving 4GB data monthly but I am only receiving 3GB. Rashkee could not assist me as she said she will escalate my query to Bradley. It is more than 24 hours and I have not received a call from Bradley to explain to me why am I paying so much than the price we agreed upon.