To unbrand your phone use this tutorial XS++ 3.1 Guide-Flashing, Customizing, Recovering - Top Sony Forums and for that use this 3 files :

MAIN: W850_R1KG001_MAIN_GENERIC_CY_RED52
FS: W850_R1KG001_FS_EUROPE_5_RED52 and
CUSTPACK: HB1-06_Gen_CDA102568_14_R5A_GENERIC_EUROPE_5


and for unlocking use this tutorial Remove SIM-lock patch generator - Top Sony Forums and follow guide for DB2020 CID52 and that is all