Unauthorised Debit Order

After noticing that my account had been debited by Digicash, on behalf of Primax Communications, I have just noticed that my wife's account has also been debited for 99,00 for the past two months. I have tried to phone Primax after getting the contact details from Digicash and left voice messages but no one gets back to me. Who are these guys and how are they getting our banking details. FNB have been great in helping cancel the Debit Orders and reversing the payments.