Seeing as I managed to unlock it myself I really don't need the i-SmartSim or phoning up '3' to get the unlock code now, but thanks for the info anyway
And I've found out that the O2 sims I couldn't get working had all expired so I sent for a new one which came yesterday and it's topped up without a problem, so that's a T-Mobile and an O2 sim I've got working in it so it appears to be unlocked!
So let's have a Sexy Party eh Cerberus
