Hi, normally I would say that you're probably stuck, but a few things to try/ask.
When was the unlock done ?
If it was very recently it might not have actually gone through yet, so it might not be unlocked for a week or two.
Did they mention JailBreak ?
This is not a true unlock, so if it was Apple that checked their system it would still show as locked.
Who was it originally locked to ?
If it was AT&T (most common in the USA) I can get that unlocked for you, but it does take up to a couple of weeks to go through (I don't need to keep the phone for all that time).
Just in case the Unlock wasn't complete in the USA tell him to put a UK SIM card in and connect the phone to iTunes, if the unlock is real and has been processed by Apple this should unlock the phone.
Hope this helps.
Thanks Dr, I will copy and paste this info and email it to him. It was locked to AT&T yes and I believe it was allegedly unlocked maybe only about a week ago.
Anyway I'll send him your advice and let you know what happens,
Thank you very much