Lodge a [broken link removed] and request a copy of the recording and confirmation of the identity of the bank staff member involved. Keep your account of the incident short and to the point; don't provide any more detail at this point than is necessary for them to locate the call in their logs. Then see what happens. If you're not satisfied with their response, after 25 working days you can refer the matter to the Financial [broken link removed].
Unfortunately, high sarcasm probably won't merit anything more than a guarded apology and a warning to the offender. You may decide to remove your custom from the bank, as far as possible, and encourage friends and family to do the same. Be sure to let the relevant manager at BoI know, if this is the outcome.