I booked our diver 2 weeks ago for Feb. They are not discontinuing the service, nor are they going to charge. They decided to just limit the number of divers per day. I believe they are doing 2 at lunch and 4 at dinner. Here's what I did:
Call the Coral Reef, and talk to a manager, or leave a message for one.
I dealt with Reginald, but many people have dealt with Debbie.
You MUST have an ADR.
They will check availablity for you, and if a slot is open, they will ask what you want on the sign. Mine will say "Nemo & Friends Welcome the Turner Family to WDW."
I am also getting the personalized menu. The manager will have you email them up to 4 family photos to put on it.
That's all I can think of! It's pretty easy, really, as long as you get a spot!
Good luck!