does anyone know how to adjust the Nav lady volume?

My problem is when I go to settings and decrease the nav volume. it stays the same. but she can get louder.
when she says"softer" its stuck at the same volume. even at its lowest setting. I tried to get into the radio service settings. Turn radio on hold select...... And tried the info... hold RDS.... but cant get into the menu?? Shes too loud..
I have a mk3 with v23 software upgrade.. 2001 x5 widescreen...
Anyone??
thanks in advance...