I cant use call barring on my nokia n 95

Neither can i?!! it asks me for a password but no password mention in manual and vodafone say its not possible!!?? if that is true which i doubt then why add it as a feature in the settings menu? it just doesn't make sense if you want to bar a specific caller and the phone asks you for a password it just doesn't make any sense. if this is true nokia might as well add options such as fly to the moon!!! surely it is possible if you want to bar a calls and they mean bar all calls why not state that? its an option which isn't an option!! makes no sense at all, if i wanted to bar all calls i would just switch my phone off which i do not want to do if i wanted to make myself unobtainable to all callers i would just switch my phone off, utterly stupid and ridiculous, either vodafone have given us an unuable pointless function or vodaphone are talking complete rubbish... infuriating!!!!