Hi Kerry,
I personally would ask the girls to leave because i am not comfortable with extra people in my flat. I wouldn't even ask for extra payment, they'll be out. And if the paying guests werent happy with that, they are free to cancel via Airbnb. And if they did keep up their noise while i was ill, and wouldn't stop after being told not to, I would be calling airbnb for advice. They may even ask them to leave if they r in breach of ur house rules!
You might be more tolerant and askfor extra payment for the girls, but then you would be opening yourself to similar behaviour for the rest of their stay.
I hope you get well soon 🙂