HL8548 limiting RF output power in GSM/EDGE (from class 4 - 2W to class 5 - 0.8W), AT+CPWC command

Hello all,
I am trying to limit the ME output power in GSM/EDGE bands (850/900 MHz) from the default 2W (class 4) to one class lower - 0.8W (class 5). There is a command AT+CPWC (Power Class) but I am having problem with it. In the documentation it states that “Module must be rebooted for the selection to be effective” but after restarting/rebooting module the old setting is active.
The command flow is like this (example):

AT+CPIN=“1234”
AT+CPWC=?
+CPWC: (0,(0,4,5)),(1,(0-2)),(2,(0-2))
AT+CPWC?
+CPWC: 4,4,0,1,1,1,1,1,2
< changing the class from 4 to 5 >:
AT+CPWC=5,0
OK
< check the class >
AT+CPWC?
+CPWC: 5,4,0,1,1,1,1,1,2
< restart the module >
AT+CPIN=“1234”
AT+CPWC?
+CPWC: 4,4,0,1,1,1,1,1,2 ← the old default setting (class 4), the new setting (class 5) is lost

Is there a way to retain the setting? Or any other way to change the class temporarily or permanently to limit the output power to 0.8W?
I have also trouble understanding the description of the CPWC command in the guide, like what are the parameters <curr_classn>, <def_classn> and how to set them.

Any help is appreciated,
Best regards,
Andy