Road freight to New Zealand

While we realize there are no roads that lead to New Zealand from anywhere, the question is logical in that there is a road that leads to the shipping docks or airports at either New Zealand or anywhere else. This means that there can be road freight to New Zealand that takes a sort of detour via sea or air. What I would really like to is in how is road freight treated once it arrives in New Zealand. I want to ship something by truck from Sydney to Auckland. Once the shipment arrives in New Zealand, will the same company continue with the delivery, or will there be a different company continue the delivery? Are there any additional costs involved once the shipment arrives in New Zealand? I need to make this shipment in a couple of weeks, so I would greatly appreciate any information your company may be able to provide.