Unauthorized Debit Order

There is an amount which was debited by Discovery Bank on my FNB account. I advised FNB that I do not authorize this debit order and as my bank they should be protecting me as their client. FNB has told me to speak to my service provider and I will sign a form from my provider which will take 5-7 working days to process. I dont have 5-7 days to wait for them to reverse my debit order. This is my account and again as my bank they should be looking out for me. I have explained numerous times that it's an unauthorized debit order but they still won't help me