Unauthorised debit orders

<p>for the past 6 months there is always a debit order that i dont know of & ddnt authorise. on my cheque acc.its always R99 or lately its R129. i have tried to cancel it at both cellphone banking / internet banking but says irreversible. i have also visited the Midrand Boulders branch , as well as the Kempton Park Festival Mall branch , but the people there seem clueless. All they do is make me sit at some phone booth & give me a phone which will be trying to contact their debit orders department ! the phone never went through for hours at both branches ! listened to their Fnb music & automated voice for hours. i really need help</p>