You should keep calling. Sometimes the person that you get just isn't that helpful and someone else is. I had to change my mother's name on a ticket (I messed up - put her middle name as her first, and with these new TSA rules that is a big boo boo). So I called the person that I got was very nice. I emailed her copies of my mothers passport and ID with her correct name and she fixed it for me. You should definitely call back.
About the passport problem, there is a way you can get her passport without both parents having to go to the Post Office. Here is the link to the State Department website that tells you about the certification that you have to get. Pretty much her dad is going to have to fill out a form (it is a certification saying that he gives his permission) that has to be notarized and then her mom will have to take it in with the Passport application.
Special Requirements for Children Under Age 16
I hope this helps.