Recently upgraded to the iPhone 12 mini, did it all through the my 02
App.
Fast easy did it 7pm Monday night, new phone arrives next day at 10am.

Nice and easy. Not a bad plan either, made use of the Black Friday deals....
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Edit - ongoing issues with voicemail and making and receiving calls.

Customer service was useless, ended up emailing CEO, executive relations have cancelled my contract penalty free and I have returned the handset,
I have moved providers and am
Much happier with a working service.

No longer recommend