*******ly activity

I have been getting deductions of R99 from my account and I did not sign for anything, when I stop the debits and desput, they somehow find a way to debit money from my account the following month. Can I please get help on how to stop this ******* debit from happening. I went on the internet to get their contact details, they have a WhatsApp number +***7 and an email ***, still waiting for their response.