Update passport number of CGI Federal

I recently renewed my passport and got a new number. But I already paid my visa fee, so on CGIFederal I see the old passport number and I cannot modify it. When I sent an email to us travel docs, they are not updating it. Instead, they are asking me to go to the appointment and get it updated on the day of biometrics.
Has anyone else been in this situation? How can I get the passport number updated?