********** transactions on my CellC Data Modem account

Just found out that My data modem got subscribed to a 'Content Service' costing me an extra R200 per month. I had no idea that anyone could just bill my line especially given I put a limit on the account. The helpful assistant in the shop showed me how to unsubscribe, but now I'm out of pocket and there was no mention of how I recover this money, just some ******* about going to a wrong website whilst using the modem can subscribe you to the this kind of thing. My understanding was that a double-opt in is required and confirmation must be given by the owner. Not sure how CellC got that confirmation from me, I would love to see it though.