Ah okay, you had bid on the tickets (I mistakenly assumed you had "won" them inferring free). It would seem that if Starwood served as the intermediary between the venue and your getting the tickets, then Starwood would be responsible for refunding the number of points you used to purchase them back, unless there is a clause somewhere in the agreement noting that they are not responsible for any schedule changes. As for your free weekend night, you might not be able to use it for your original purposes but you certainly have not lost it.