Don't do what she wants!
她故意逼你炒她,倍錢俾她, this is what she wants. To get $ 3580 and then find a new employer.
From now on, give her many many jobs everyday, esp the jobs she doesn't like, heavy jobs like clean all under the beds, clean all the walls,...., give her the food unwanted.......
She will resign, because possibly she already got a new job after this holiday! Don't fire her, she will fire you, maybe she needs to go to her new employer very soon and she cannot wait, then she will resign.
Good luck!