Here's a list with several methods. Hopefully one of them will work for you. Wishing you the best.
one way to keep flies away is to fill a ziploc bag 1/2 way with water add several copper pennies and hang near where you are. It really works! and here are ideas for killing flies
Here are some tips for getting them out of your house: https://www.craftylittlegnome.com/flies-house-suddenly/