Vodacom *******

A month ago I got called by Vodacom asking me if I'd like to migrate my package to a data package. The package I was currently on just gave me airtime and I hardly used airtime so I agreed as they told me the amount of the new package was similar to the total amount I was already paying so I agreed. I received an invoice and saw that my monthly debit was going to be double what it initially was. After calling them, they told me that I had agreed to that amount and that I had to pay. I told the lady I spoke to, in what world would someone migrate their package and pay double what they were initially paying. It didn't make any sense. So they used the fact that I was paying a particular amount for my device and the package, and quoted me with a package of a similar price and are now using that as justification for me agreeing to pay that amount but nowhere in that initial phone call did they clarify to me that I would now be paying double able what I was paying prior to that.