I have messaged the manufacturer and hopefully they can offer some insight. I will try a few more things today and report back.

I have made 1 step forward 20 steps backwards.
I added to the (sound) in sys.txt so I ended up with is
[sound]
ding_muted=1
csv_voice_enabled="1"
pause_mp3_sooner = 500
dev_buffer_size=200
android_muting_device=0
guidance_distance_offset=50
;### (1) read by dex file, 0 fix for Android 4.x
;android_muting_device=1
;auto_mute=1 ;(0)ICS/JB
;keep_alive_speaker= ;(0)
;speaker_resume_sec= ;(3)
;allow_no_buffer_return_on_zero_volume= ;(0)
;logarithmic_volume= ;(0)
;compressor_switches_on_ui= ;(0)
;enable_silence_playing_muting_device= ;(0)
dynamic_volume_type=1
dev_channels=1

And it work perfectly.
I then tried to change the sys.txt on my other car running iGO_Pal (iGO719WD) and now I cannot get iGO to load at all, just the old "global_cgf not found" error.
I have pulled the head unit from the vehicle so I can change the sd card and have tried all sorts of things but still no luck with anything.
This seems crazy.
Hope some one can help.

All working perfect now see Global_cfg not found thread for details.
Thanks everyone for the help.
Baz