Hello MKT!
1)I was mistaken when I said that NITZ is on BCCH. It is carried in MM_info message on dedicated mode.
2)NITZ – is Network Identification and Time Zone. Yes you can modify it in BSS.
3)You can not change the priority order because it is specified in 3gpp 22.101. The only way to resolve your problem is old SIM by new SIM (with new operator name) replacement.
Regards, Pan