honestly the best way to get what they call a "trace" on the tracking is to take your receipt with the number on it direct to your local PO and fill out the form requesting a trace

I was shocked to learn the PO phone number is "outsourced" and have learned that doing things thru the central number or website often can drag on an on and on

once you fill out the form (which being it is a month already falls within their "trace" time limits) then they are obliged to track it's movement, which they can..as dahlek mentioned, it gets scanned along the way and that shows when one does the trace so its whole journey till it fell off their radar can be tracked
They found one of my customer's packages in one of the depots on a shelf once. It had been missing almost 6 weeks
dont give up! but do go there in person with the receipt and you may be surprised at how quickly it could be found!