Call back and get a different person, if you can. I got a mean person the first time this happened to me a couple of years ago (I can't remember why I couldn't serve other than I have children and daycare and it would have been COMPLETELY inconvenient). She told me there was no way to change it. Well, after being very upset for a day, I called back to "argue" my case and I ended up getting a very nice woman who said that the first lady must have been "so and so" and she put on my record that I shouldn't be called up for a few more years.
SOOO, it's just like getting different CM's when you call Disney. Call back and see if you can talk to someone else (even ask and get people's names). I'm sure there must be a way to get excused during the duration of your trip.
Good luck. I feel for you. What a stress you don't need. I wouldn't have even thought of this happening; I usually just worry about us staying well and travelling to WDW safely!