Thanks for fast response.
I've found another firmware
W880_R1KG001_FS_EUROPE_4_RED52.fbn
W880_R1KG001_MAIN_GENERIC_RED52.mbn
I tried the guide, but the W880i still remains locked and branded (as told by SEtool 2 Lite) but it seems to accept the new sim card and I can't come into the phone and it tells that there are faults in the configuration, contact bla bla ... I'll try to flash it again