I’m late to this party, but just for future reference:
In lots of cases you can use RX4 or 5 to remove an amazing amount of background noise. In most cases it won’t be production quality when you start with very low quality audio, but if you know what you’re doing you can make huge progress.
The Audacity noise reduction is not very effective, but RX is in a different league.
How long is the audio? Can you post a sample? (I’m new to this forum, I don’t know if that’s allowed.)
Or I can set up a Google drive share and I’ll give it a few minutes with RX. It really depends on the exact nature of the background, but the Dialog Denoiser is pretty slick.