I'm amazed by most of the responses. Why is this not like the flat Fanta example? The roommate contracted for a shared room at a particular rate, and got exactly what she bargained for. If I read the OP's description correctly, the roommate was not even aware of the problem. The OP contracted for a shared room at that rate, did not get what she bargained for, and negotiated a credit. She suffered all the inconvenience and did all the work. Why does the roommate deserve a share any more than any other guest in the hotel?