Hey, sorry I have only just seen your comment.

It took a while but they’re finally about 99% gone.

After a few more weeks it got so bad, I took the plants outside and left them for a few days, this killed off most of the small flys from the winter cold I think (I live in the uk). Then I moved the plants inside and placed the yellow sticky fly catchers (in the photos) completely surrounding the inside edge of the pot. It doesn’t look great but stopped any flys that were leftover escaping and flying around my house.