How much can I request to reduce my rent?

My lease started on Sep.1st, 2009. However when I moved in, my room was not ready yet and I couldn't unpack my stuff until Sep. 16th. I had been living with a suitcase as if I was traveling, which was very uncomfortable. The landlord said she could pay back for 10 days. (I don't know why it's 10 days, but I have no intention to discuss about this number.) Now she says she doesn't know how much she should pay back, because I slept in the house and I only couldn't unpack my stuff. Can't I get back the 2/3 or the monthly amount? If not, how much is reasonable?