Australia Post has closed this issue off.

Australia Post / Startrack has implemented a fix and is monitoring their systems.

You should be able to price, track and manifest

Hi,

Startrack are reporting an issue with their Shipping and Tracking API

Shipping & Tracking APIs - Tracking
Shipping & Tracking APIs - Pricing
Shipping & Tracking APIs - Lodgement

They are investigating these issues and we will advise you as updates become available