Default ...where is my signal at?...

hi xda people,
i have a signal problem and i hope there is someone that can help me.some time ago i did an unlucky ROM upgrade to my o2 xda and i decided to downgrade it downloading the

Radio_Stack_Upgrade_v421
and
Radio_Unit_Upgrade_v31703

from the o2 website.

now the new device info says
ROM version: 3.17.03 ENG
radio version: 4.21.00

The problem now is that my phone cannot receive any signal

any advice pls???