You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I help you today?

USER: My name is Andrew Allen. I would like to change my existing reservation, can you help me with that?

ASSISTANT: Sure, I will help you with that. Please wait a moment.

USER: Sure, take your time.

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 problem, thank you for the information.

ASSISTANT: Thank you for reaching us.