406 LX 1997 1.9 Diesel - Key Pad Number Change

Please can anyone advise how to change security number on hidden key-pad.
My 406 user manual does not cover it. Further Question: I only have one
key / remote lock/unlock. How much to get a duplicate - is it just a
remote lock or is there a security enabler/disabler combine?

 

in my 405 handbook it states,
switch on the ignition
enter the code already stored in the memory,
press button C
enter the new 4 digit code,
press button C to confirm
confirmation is 4 flashes of the green light and 4 bleeps
that's it
HTH
Fitzy