I'm sorry to say that Dan is simply following procedures here.
BNZ will never confirm that a staff member works for them, nor will they confirm contact details for staff members. (Emails, mobile numbers or locations)
This is related to security of the staff, as well as security of the customers
Fraudsters often call up BNZ requesting staff information. If any details are confirmed they call BNZ customers advising this said staff member is concerned about their account and uses this to obtain details that will allow the fraudsters access to the customers funds
In turn the customer gets worried, calls BNZ, again if we confirm the staff member works for BNZ then both the customer and bank are conned and by the time we realise what has happened, the customers money is long gone.
If you want to talk to someone higher up, it would be a case of asking for your details to be forwarded to the relevant department where someone will be in contact.