***** on bill - charging unauthorised items

I received an sms towards the end of October stating that my(voluntary soft lock of R1500) had been reached and I will no longer be able to make calls.I looked at my balances online and found that I had ample free voice and data available. After phoning the call centre I was informed that it was subscription to a company Opera telecom for a product called Xcon and that I was charged R50 a day! I have never subscribed for this, and I did not give Vodacom permission to load this money on my Vodacom contract. Very little help was offered as to what I could to rectify the situation. What is worse, Vodacom asked me if they can cancel these subscriptions? Vodacom did this over the phone and I received an sms to this effect. This surely indicates they are aware of these issues and are not protecting their customers against ***** like this? What can I do to recover my money? Thank you in anticipation,<br>