Welcome to Vodafone Community
I received my upgrade today by post in the form of an iPhone 4s however I cannot activate it. I have tried both via Wi-Fi and iTunes but am just told that the server is unavailable or that my request cannot be answered at this time. I've also reset the phone and put it into recovery mode but still no joy.
Anyone have any ideas?
The apple registration server could be down or having maintenance which is probably why it's not letting you register your iPhone. Trying leaving the phone off for an hour or so and try again using wifi first as this is apple's preferred way of registering but if no hope again try through itunes as you have previously done and if you still have no hope by tomorrow I would take it to your vodafone store and ask them for a new on as it may be an internal fault with the phone.
I hope this helps and I hope you get your Iphone working soon!