But today I solved my problem and got my XDA IIs SIM unlocked.
Within 30 minutes.
I happend across an official O2 email address that I sent an (abbreviated) SIM unlock request, briefly stating why I needed my XDA IIs to be SIM unlocked, and providing my O2 account number and the handset IMEI number. 30 minutes later and I was emailed back an unlock code.
No ifs, no buts, no questions asked and no payment required.
I placed my Orange SIM card in the IIs, waited for it to boot, entered the code and was greeted with "Unlock Code Accepted." Both dialling out and receiving calls on my Orange account no problemo.
I should state that this email address appears not to be publicly available on any of the O2 websites and I happened across it quite by chance.
I don't know the whys and the wherefores of all this, but it seems to me that if the email address was flooded with requests to SIM unlock, someone higher up the O2 chain might notice and put a stop to it all. I'd rather not have anyone - even someone I don't know - get a severe rap on the knuckles for being an anonymous benefactor to XDA users
Bearing the above in mind, I'm not going to directly post the email address, but will gladly pass it on via PM.
FYI: before I handed out my IMEI and contract number, I done a WHOIS search on the email address domain (you know, the bit after the @ symbol) and I verified it as legitimately belonging to O2.
Lastly: I'm guessing that this process would apply to any other O2 device such as the XDA IIi and II mini... if you own an XDA II or earlier, there are already free SIM unlock tools out there on the web.
Hope this helps, folks.