Total garbage if they don't let you switch dealers. I had a similar problem of the system saying my preferred dealer was unavailable, never selected any dealer, it ONLY gave me one choice, and I have a dozen dealers within an hour of my house.
Email back from Autonation Ford in St Petersburg, FL:
"TBD on ADM" and they said "We won't accept XPLAN, as most dealers won't" I guess I'm moving my reservation when the time is right.