I have some 3gpp recordings that I need to enhance. I would like to give more balance to the left stereo and change the frequency levels to make the recording clearer and convert it all to mp3 or wav. Is it possible to use my existing vlc media player to do this or are there any recomended free or low cost alternatives if not?
Audacity is a good free and open-source audio software. You should be able to adjust the left-right pan easily.
But sadly just converting a file won't improve it (actually recompressing it could make it worst). The 3gp files I've seen before were very small and recorded with my old phone, so of poor quality to start with. Maybe you can experiment with the equalizer and low/high pass filters, but don't expect miracles.