Originally Posted by firestone9x
Since your phone has an unlocked boot loader, it will have problems downloading the official phone updates released by Sony. You may have to manually flash 4.4.4 to your phone via some other third part software.
He means unlocked to any networks, not bootloader unlocked.
I also bought a SIM free device in the UK and I haven't had the update either on the handset, or by plugging it into a PC. It is based on serial number, so the newer your device, the longer it will take to get the update. I bought mine in April.
Sony Xperia Z1 Compact, Asus T100, iPad mini, MacBook Pro retina 13"