M4A is the audio layer taken from an MPEG4 video, isn't it? You could try
>Vidomi< - I'm not sure if they've picked up the correct codecs yet for this. Do you have the original video sources?
The current Goldwave (not free) incarnation may be able to do the conversion. Don't think Audacity will have caught up yet.
Or try googling "M4A MP3 converter".
