good for you to send her something...i think you'll get better satisfaction this way since obvioulsy face to face ain';t gonna work with her!
i like the letter...its not the tone i personally would use (i'm more frontal and in your face) but if it works for you than by all means sned it.
her action are unacceptable. yes emergencies happen. people get sick, have flats, etc. but 8 times...thats pushing it...and even if she has the worst luck of anyone she should be apologetic...not defensive.
hert twisting it into your problems is a giant red flag.
good luck. take no prisoners. take no crap. remember YOU PAY HER...YOU ARE HER BOSS...SHE OWES YOU HER RESPECT AS WELL.
stumpy