So after a few issues with one ear stopping working, always resolved by a reboot, a couple of months ago the phone stopped playing anything through headphones, and would just play through the phone speakers when they were plugged in. That was for a couple of days, and then it started working again, so I assumed that it was just some software bug. But then a few weeks ago headphones stopped again, rebooting does not help. Updated the OS today and no issue, finally resorted to a hard reset and still not working. On the dev preview, but I can only assume this is a hardware issue, so off the Nokia shop, hopefully still in warranty!