If a flight TIME has changed, then there's absolutely no need to call, since DME is hooked into the airlines' and airport's computer systems ... they're system probably noted the change before passengers were notified!
But when the flight NUMBER has changed, it is absolutely vital that you contact DME (or have your travel agent do so, if that's how you booked your resort room). They will not know that your flight number changed. Under normal circumstances, this wouldn't matter, since, as has already been pointed out, they have your reservation in the system and there are "always" buses running, so you'll get your ride, etc. But if your flight gets very very delayed and due to this delay you don't arrive until the wee hours of the morning, DME won't know to wait around for you if they aren't expecting you that late.
In other words, let's say your flight is scheduled to arrive at 7:00 p.m., but due to delays it actually arrives at MCO at 2:00 a.m. If DME has your correct flight #, they'll know you're getting in that late due to the delay, and they'll be waiting for you. But if they don't know you are on that flight #, they won't know to wait for you. If there are no later reservations or delayed flights, DME closes up shop for the night at 11:00 p.m. But as long as they know they are waiting for people, it can be a 24 hour operation.
So make sure you get that new flight number info to them.
DME reservations are a function of resort reservations, not flight reservations. So if a travel agent made your resort reservation, then the travel agent must make the DME reservation and any changes to it. This applies even if you bought your airfare yourself ... the "ownership" of the DME reservation is tied to the resort reservation, not the flight.
