PASSPORT NOT ID

i get a mail from the bank saying i can come collect my american express card, phone the bank and ask if it there, no it has been sent back because it as been here for more then so many days, i ask what card they say petrol card, i say no there is a business card , they look in the drawer find it , i ask what i need to collect, water and lights acc plus my id, so i take my passport because my id book has been taken by midnight shoppers and dont have one yet, only to stand in a queue for ten min , and then get told a passport is not id you need a id book, since when is a passport not proof of id, i have used it ever since my id book has been ****** , and never had a problem, why do nedbank not accept a passport as id ,