Help SF2 "Mobile Network Not Available" please help !


Hi Guys,
I'm really hoping somebody can help,
I recently bought a used but excellent condition SF2 for my daughter for Christmas, I switched it on to check it worked, but didn't try a sim card in, so don't know if my issue was always there, or only happened after unlocking and flashing the ROM.
I followed this guide to unlock:
sanfranciscoandroid dot co dot uk/android/unlock-orange-san-francisco-ii/how-to-unlock-the-orange-san-francisco-ii-for-free/
and then the other guide showing how to install Android 4, it was after this that I noticed that when I tried my wife's Orange sim in the phone, there is no network coverage, I also tried my daughter's Asda PAYG sim (which I believe is on Vodafone) with the same result.
I though the phone was faulty, but decided to try my "3" sim in, and that worked fine.
I have tried the other 2 sims in several times since, each with the same result.
I'm really at a loss as it's only a few days to Christmas and I'd really like to get it sorted if possible.
I then used this guide to flash an ICS ROM, but nothing has changed.

Everything else seems fine, and WIFI works perfectly, but there is a little cross constantly on the network signal bar.

Any help or advice greatly appreciated

Many thanks in advance