Getting Vodafone network to show on mobile

I have a bog standard Nokia 2730 phone that was originally issued when I joined TelstraClear 4 years ago, and is now happily running with Vodafone (was same network, of course ).However, the network advisory on the main start-up screen still shows TelstraClear as the network, yet overseas it will switch to whatever is chosen locally there, then reverts back to TC here in NZ.I've looked at the settings and VF is shown as the config setting, so why is TC still showing? Can this be changed on the phone or is VF sending a signal from their systems that identifies the old network name?Would be nice to be 'loyal' to VF R.