FNB Debit order reversal refusal

I am very gutted by the way FNB has been treating us lately. I have been trying to reverse an unauthorised debit order for the past 6 days and today they keep on telling me they having system errors or challenges because they changed their systems. This is unacceptable as there is no communication to FNB users. Calling their call centre and be placed on hold for more than 30 minutes only for your queries not to be resolved is very wrong. How long will it take for the systems to be resolved so that they can assist us?