My phone went missing on 7 May.  It's a Samsung C100, switched off and
with both phone and SIM digitally locked; bought from Virgin, but
unlocked by them.  Although it's most likely that it is mislaid and
still in my home, it's still not yet turned up and so I can't, most
improbable as it seems, absolutely rule out theft.

I rang Virgin CS, and they've suspended the SIM and say they can
transfer my PAYG credit to a replacement one, so no problem there.
But when I asked about their also blocking the IMEI, I was told that,
once they did this, it would not be unblockable should the phone turn
up again, and that I'd just have to get a new one.

This seems to me a ridiculously rigid and wasteful practice, and I don't
understand why it should be so.  I'd like to maximise the chances of
the phone being found and, should it be the case, any theft tracked.
But I don't want in effect to have to write off the phone in the
process.  I don't, btw, think it's worth making an insurance claim
for it.

What I'm wondering now is:

1) Is the advice from Virgin true?  Is there really no way of
   reversing an IMEI block?
2) Is there any effective difference, if I do want to notify the phone
as lost or stolen, between notifying (a) Police (b) Virgin (c) the
National Mobile Phone Register on www.immobilise.com?
3) Are there any public documents available setting out full details
of the national IMEI phone blocking protocols, practice, and procedures?
4) Any other advice? :)