If you want to call the resort, they won't have your reservation in their system until 3 or 4 days prior to your arrival. Because many of the calls now go directly to a call answering service, you may need to be very clear that you want to speak with the room assigning department of the Pop. They might end up sending you back to CRO, where you probably made your initial reservation.
Another option is to send a fax, which will go where it's intended, but there's no guarantee that it will be looked at.
Here's the phone and fax information from Allears, 407-938-4000
Fax - 407-938-4040