Welcome to the Dis

. If you are on the reservation, you will be able to call and make changes/have a discount applied.
As with all discounts, there are only so many rooms available at a discount. If the resort/room type you currently have booked is available with the discount, your existing reservation can easily be modified without cancelling/rebooking. Cancelling and rebooking is only needed when you go from one reservation type to the other (RO to package, and vice versa). Room only and packages are different reservation systems, so money paid toward one cannot be applied to the other. If you can book first thing in the morning, sometimes that's the best as far as having a better chance of getting exactly what you want. But with that said, I have called/checked online to book a trip under a promo days after it had been released and have gotten what I wanted

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