A new firmware with build number 14.2.A.1.124 has been certified for both the Xperia Z1 (C6902, C6903, C6943, C6906) and Xperia Z Ultra (C6802, C6833, C6843, C6806). This new build follows on from the recent certification of build version 14.2.A.1.114, which was unreleased. This new update is likely to fix a number of bugs that people are having with the Android 4.3 update as well as introducing the white balance app too.
Thanks DetmL, Mohit and schickel!