You can cancel some or all of the FAS before sailing as long as you do it more than 3 days in advance. If you don't drink much or don't want the specialty dining, just call your TA and have it removed. You said you booked a week before the sailing -- do you still have at least 3 days left or are you already within that window? If you can't cancel FAS or if you still have OBC to spend, you could: Pay for on-board activities, like an escape room, Canvas by U painting class, or the go cart
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