I think your best bet might be to drop into a Vodafone shop. I can't see any reason why you shouldn't be able to get this device online (I'm sure I'm come across other Nexusus that are) and it's probably something that's easy to fix if you've got the thing in front of you.
One further thought: it sounds as though you're PAYG. You are using the PAYG settings, aren't you? I may have linked to the contract ones.
Oh, and I'll move this thread to the Device board as someone there might pick it up and know the answer.
