http://www.sammobile.com/firmwares/1...e=BTU#firmware
This page has the 4.3 firmware for unlocked handsets and you can install if you know how.
However they don't list 4.3 for some of the UK networks so I don't know if the branded versions are actually out yet.
Are you sure your phone is totally unlocked and free of any network brnading?
Your phone is running a UK firmware. Thats what the XX means in the PDA.
However the CSC I9300OJVEMF1 is Algerian. Thats what the OJV refers too.