Unauthorised debit order

I just got an sms that tells me that a debit order of R98 has been lodged on my account but I have no dealings none what so ever with this company. When I try to call them on the number they provided, it just rings, no answer, phoned the number I got on their website, no answer still. I want them to cancel this debit order before it even goes through my account as I am not prepared to pay bank charges for this nonsense.