Vodacom unfair treatment of customer

I was contacted in December 2017 by a VODACOM agent or an agent acting on behalf of Vodacom. They told me that they notice that I am recharging often and would like to offer me a flexi 500 contract..as I am currently on a smart top up 200, I enquired a few times if this was an ADD ON contract to which they agreed. The next month I noticed my smart top up has been cancelled and I call to enquire as to the reason, and I am sent from department to department, each claiming that that they have no idea as to what has occurred, and all they can see is that I have been migrated to a FLEXI 500. For a whole month I received no feed back, and nobody claiming responsiblilty for the mess up. I even asked them to replay the phone calls to prove that not once did I agree to to migrate from smart top up to Flexi 500, but only agreed to have flexi 500 as an ADD ON. A month later everything is back to normal, but I notice my premium has increased. Upon investigating my invoice, I notice that I have been invoiced an amount of R1700-00 for migration fees. How can this be fair when I did not agree anywhere that I would like to migrate, and was only accepting the FLEXI 500 as an ADD ON. If the flexi 500 was not an option as an add on, then why the didn't THE AGENT inform me???? I would like for this to be taken up with higher management and for this amount to be waived and for the excess amount debited off my account be reversed. I am not even asking for my time and resources be reimbursed in this regard, just asking for some fairness, and maybe a years worth of free data. That's all. Thank you.