I initially phoned Microsoft Support (13 20 58 - Australia) who ran me through troubleshooting then told be to send it in for repair to their service centre. I was emailed reply paid shipping labels to attach and followed their shipping instructions.
My contact with support has mostly been the 13 20 58 number (Aust), although this has apparently been escalated to a team that I've been told will definitely contact me with updates. (But since these promised phone calls/emails have never happened I'm
assuming escalation is a waste of time)
The device was delivered (as confirmed by tracking information) on 29th Jan 2014, but their service status webpage continues to show only "Order has been created". When I called to query what was going on I got the distinct impression that they believed
it had not been delivered (i.e. lost)