Using the latest audio software, filtering, EQ and noise reduction, I can reduce the background to expose whatever voice print is on the file.
I have a fully equipped audio studio, using Adobe Audition, Sony, and others. Ideally, the file should be uncompressed, not mp3. I will transfer the compressed file to .wav and work on that. It won't remove the compression, but it will eliminate any further degradation of the audio whilst exposing the speech.
My bid may be higher than others, but I am BBC trained and have worked in restricted environments on this kind of project.