Vendor, thanks for the encouragement
While I was waiting I thought I should take another look at the SH3C manual and I think I know what I did wrong...
I think (untested yet!) that what I need to do is put the radio files into folders for that
exact date so they only play once rather than being "randomised" - as I am now in between two folder dates from the pre-installed SH3C radio broadcasts, I think it is defaulting to the older folder but only playing the files I added as I have skipped through like a hundred fifty or more times and never got JScones Radio.wav file more than once a patrol.
It warrants further looking into but not tonight or I will never get through the Kiel canal and sink anything!
Cheers
Stokey