Personal information not safe with MTN

I have had a very bad experience with Mtn, South Africa. I have had contract with them for many years and two years ago I added a new number, thus taking a second contract. I then finished paying in June 2018 and never upgraded my contract again. I then indicated to an agent that called me that I have no interest in upgrading, but I Wil only take a month to month contract. That went through. To my surprise, yesterday, 25.09.18 I received an sms indicating that I have successfully upgraded my contract and my new upgrade will be due on the 25.09.2020. I then immediately called Mtn and I was out through various departments until I landed to their retention department. The lady I spoke to, Cynthia said indeed the account has been upgraded and they cannot tell me who but was done through their department. I disputed the act and said I have no knowledge of the upgrade. The upgrade was made on an IPhone 10 plus at at cost of R899. 00 per month. Cynthia then said she has excalated the matter to their ***** department. I asked that I kindly send me the proof of what she sent to ***** department, she failed. Again today, 26.09.18 I made another call as I was extremely frustrated because of having to pay something I bear no knowledge of. I spoke now to Kamogelo, who also confirmed that an upgrade has been made. I asked the possibility of that happening, she said someone has phone them and I asked who, she did know know. I question that fact that even if someone had called, there is no way that a person can know all those security questions asked before opening a client's file. I also highlighted that even if that could have been the case, we also cannot rule that fact that someone within their department could have done so. We do trust these companies with our personal information and this is extremely disappointing. She then said the order has been send to their courier company and I asked her to provide me with the address they have given to the courier company and she said she cannot see that on the system. That was alarming because the courier will have to be provided with the address by MTN, but if she says she cannot see, that was surprising. She then advised that I go make an affidavit indicating that I did not do am upgrade and send to them with the copy of my ID, while she escalates the matter to ***** department and I must note that nothing will be done to the queiry until all the documents asked are sent. She then provided me with the couriers contacts details and when I called, they was no phone received but they advised that I must keep phoning maybe it's on its way still. I am really not happy with this ***** element and I was them to clear this act as soon as possible. I am not paying for something I do no need and certainly did not as for

Kindly assist