Tell her that if she keeps leaving the heating on in an empty house, you might have to increase her rent to pay for this. Very often, money focusses the mind somewhat!
Migsy; heating on full blast AND the windows open...liked to be warm and have fresh air nothing wrong with that, I thought you were a convertible driver!!LOL
I got rid of my lodger, same sort of problems, he was like a locust, consumed every thing in sight then buggered off!!