Billing for WASP service (Opera Telecom)

Vodacome has been billing me excessively the past 2 months for WASP services that I did not subscribe for, I enquired on the matter and was informed that I have no other choice than to pay for this account. The additional billing amounts to about R3 000 while my normal monthly account amounts to about R200. I would not subscribe for a service that I cannot afford and I do not have the funds to pay or this service, Vodacom has no idea what this service is for, nor could I be provided with any proof that I subscribed to such service. I feel it is unfair to force me to pay for a service I did not receive any benefit from. After logging a call with Vodacom, I did not receive any response. In addition, Vodacom cannot block future subscriptions to this unknown service and is, therefore, not protecting their customers in any way. I expect to be refunded for this mistake by Vodacom or Opera Telecom but it should not be my problem to resolve the matter.