unauthorized debit orders

Today I received an sms notification from fnb advising than amount of R1087.60 was debit from my account. Due my knowledge I was not aware that I had authorized such debit order. I however went into FNB today and was informed by the consultant that my account was being debited by ABSA BUREAU SERVICES. I have never heard of this people nor do I have any such dealings with them. I find it very unprofessional that FNB would allow debit orders to go of a persons account without any form of authorization, Its is not the first time that I am experiencing such issues with FNB as I have had numerous issues with FNB like this and I had to personally go into the bank to sort this out. Fnb is becoming a pathetic bank to bank with. They allow just any TOM **** AND HARRY to debit a persons account and I AM SUPPOSE TO BE LIABLE FOR ALL THE CHARGES INVOLVED WHEREAS FNB MADE THE ***** UP BY ALLOWING UNKOWN PEOPLE TO DEBIT ACCOUNTS. FNB IS NOT SHY WITH REGARDS TO THEIR STEEP BANK CHARGES THAT THEY HAVE..