You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Christine Mitchell.

ASSISTANT: How may I serve you today?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, please wait a moment I will check the reservation list.

USER: Ok.

ASSISTANT: Thank you for waiting. I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: No issue. Thank you.

ASSISTANT: Thank you for opting us.