Postcode Impossible

Yesterday, I took a pre-paid parcel to the local Post Shop. It was being sent to Waipawa and included a post code. The female assistant looked at the address then asked me which Waipawa it was (yeah right, there were four of them in New Zealand). "I don't know but you have the post code on the parcel," I said. To my utter astonishment she replied: "We can't enter or look up post codes on our system." Huh? The four digits might be a secret code to them?