Unauthorised deductions

I Have been a customer of Vodacom for about 35 years. I am retired now and have changed to prepaid. This month I discovered that Vodacom started to deduct R7.00 daily from my prepaid airtime. I wrote an email, but only after my second email got an automated response. I send a WhatsApp message with also no response. Today I managed to speak to one of their agents. He adamantly told me that is is my mistake and that I have signed up to some sort of adverti*****t, but he is not able to tell my for which Ad. He mentioned something like winsports ?? When I googled winsports I discovered that many people complained about the same ******** deductions. I did not give Vodacom any permission to deduct from my airtime, Vodacom did unauthorised deductions from my airtime.