How do I change numbers to use with iMessage?

[iMore Question]

I went to nz and used a local SIM card to message on my iPhone and iPad. On return to Australia this number persists when sending messages using my Australian SIM card. My current number does not appear as an option on iMessage addresses. I have tried:
- putting messages on and off
- resetting network
-resetting all settings in general
- rebooting phone
Nothing has worked.
I need to remove the nz number and add my own current number. Can you help please?

 

[iOS Gravity]

Remove NZ sim. Reset Network settings. Put in new sim.

 

[iOS Gravity]

If you deeply want it fixed and don't mind, do a restore.