Setting Satnav volume

Hi All,
Perhaps I'm missing something, but I've tried to adjust the maximum volume of the Nav by the audio presets and it only goes down to "8" from a maximum of 20.
Is at all possible to reduce it further or is there a minimum allowable value?
Neither myself nor the dealer seem to be able to work it out.
Thanks in advance for your assistance.

Try turning the volume knob when the voice is saying a command. But I'd be surprised if there was a limit on the minimum. Have you tried changing all the volume presets lower incase it won't go lower than another setting.

I turned off the voice (just hit the speaker picture on the top bar when in Nav), never use it, like it to just show me.

If you go into settings you can adjust various volume limits. Been a while since I did it but it's in the manual.
Cheers

and if you don't want any voice there is a "mute" button on the touch screen

Thanks: I tried all of the above and no go. As for adjusting while talking, it only works for that one event/sentence. Efforts to enter the presets only allow reduction to a minimum of level "8".