Change of MNC in APN settings

[ragstoriches]

Whenever I change MNC code in APN settings,Settings won't save,i tried many things but nothing worked

is there any way it can be done?
any software, by command prompt etc etc?

help will really be appreciated
thanx


EDIT:

in chinese mobiles, we can do it easily (i own one)
in network settings there is an option named 'PREFERENCES'
in there all MNC codes are listed, all you have to do is just select one and change its priority to '1'