Unauthorised Billing (Potential ****)

I reviewed my most recent Vodacom invoice and found a line item called \Content Services\" to the value of R223.99. I immediately phoned Vodacom to query. They said I had subscribed to a service provided for by Smartcall Technology Solutions (STS) on 28-01-2016. I have absolutely no recollection of subscribing to such a service, I have never subscribed to anything of this nature, in fact I make a point of avoiding these services altogether. I reviewed my SMS history, as well as internet browsing history on date 28-01-2016 and found no record of ever subscribing. Vodacom said there's nothing they can do to reverse the charges