ubernoob: Update from Sony support NZ. Apparently using my phone imei number there are no more updates planned for my phone. He was very diplomatic and knew later international updates were released for the Z5 but was certain there would be no more updates for ISP branded phones
So there you go.
I asked Spark and got this back -
"The latest build we have tested for the Z5 is 7.0 – which we approved on 28/02/2017. We don’t have a new build from Sony on the radar at this stage, we've asked them to see if we will get it or not. "
Basically it seems if you want 7.1.1 you'll need to flash it yourself. Android is so broken.