Australian post parcel question?

I bought a few things off eBay recently and got a card in my letter box the other day saying there are two parcels waiting at my local Australia post. I went and showed the card and the gave me one package. only after did I realize that the card had said two parcels. a few other things have arrived and just been left at my front porch. I'm afraid that something is sitting at the post office though waiting to be picked up. How long do they keep the packages for at the post office and do you think I should go and ask? thanks