UNAUTHORISED DATA CONVERSION

On the 6th of May I loaded R 150 airtime and to my surprise R100 was automatically converted to data of 1G for 14 Days. I called the Call Centre and they claimed that I must have selected recurring option with my previous data conversion. Now what is surprising is that the details of the data on the Vodacom App read as "once-off" and not "recurring" as claimed by the Call Centre agent. When I told them about that fact,they now claim it to be a "system error". I received no sms notification for this purchase whatsoever like I do with all other data purchases I manually make,why is that? There's a level of ********ity in committing my money to data of which Vodacom conveniently cannot convert back to airtime and as the Call Centre agent told me "I must just use the data". No, I want my R100 airtime back so that I can choose what to do with it. They can keep their data for all I care...I want my money.