Yes,they do. It's usually more efficient to call than to keep using the web. Usually the CM can search a lot faster and easier. The most likely rooms will not be in the value resorts. The cancellations are usually Deluxe and occasionally a moderate.
From our experience, there are a some people that book just in case and then do not go. Others will book 2 resorts (not me, but I have heard from people we know

) as they have not decided which one they plan to go to and then cancel the second reservation once a decision is made. You can keep trying to call. Usually it is around that 45 day window where payments are due that everyone tends to cancel or postpone if they cannot go.