NZ post pick up

You are quite right, by offering the book a courier service, they leave themselves open for this kind of criticism.

I do doubt if they are liable though, they are just a platform offering a connection rather than service, think of it like Trivago or any other hotel booking site, if you book a hotel room, and arrive to find a roach infestation, its not the booking sites fault, its the hotel, I would have thought that this is the same situation, your problem is with NZ post service not the service that Trade Me have provided - unless the booking never went through, then in that case T-Me service has failed.

If you are in Christchurch the courier service might have been held up by the big Bush Fire on the Port Hills today (which is still ongoing btw), and it may get picked up first thing tomorrow, if you are somewhere else, just give NZ post a ring have  your tracking number ready and just whats up.

NZ Post were having problems last week in picking up parcels, and sending parcels to and from Auckland. I only found out after looking up their delivery page....something to do with unplanned maintenance. A parcel to a client across Auckland took 3 working days by courier post, when usually it's targeted overnight.

Sent them this message...

Booked a courier, followed all the instructions you show.
Courier (NZ Post) did NOT pickup. We rang them, it was because the item was not in the letterbox. They will not ring, knock, or come to the door or driveway.  They wanted a sticker on it, when I specifically selected "courier to print and attach sticker"
Trade Me instructions DO NOT say this.  Considering how many hundreds of pickups must be done, it is DISAPPOINTING that Trade Me can't convey NZ Posts requirements properly.  One sentence, and a whole lot of missing connections could be avoided.
  I consider trade me have not met their obligations under the Fair Trading Act and this is a serious and ongoing breach.  The buyer picked up the item, so a refund of the courier fee is due to them. I contracted with you to organise the pickup, you failed. Trade Me is well known for ignoring these sorts of complaints, so here's to advise you I will keep following this up until you do something about it.