Radio Service Menu - Help needed

[brucemillar]

2001 - 4.4i
MKIV Nav - 16:9 screen
Factory fitted radio and CD changer.

My Nav is running V31 OS.

Help I cannot access the service menu for the radio.

Ihave:

Pressed "info" no joy - nothing happens.
Pressed and held tone/select individually on the select side of the button (30 secs) then switched off and on again and tried the tone side of the button. No joy nothing changes.

If I hold the FM button down with the radio on (I get the RDS/REG etc) but if I try and select any of these it puts the display straight back to the current radio station without making any change.

So how do I get into the radio service menu. I need to adjust the radio traffic broadcast volume.

Many Thanks

Bruce