Making me pay for Something i didnt request

I got my Monthly invoice a day or 2 and saw that Vodacom is charging me extra R500 for additional services, and then so I called them and they said I should pay for it, according to them my mother subscribed to a **** site. REALLY??? how can They let this happen R20 a day for something you don't use??? We wont pay that that is very unprofessional I am disgusded!!!