You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I aid you?

USER: I am Laura Green. I need o change my existing reservation, Can you help me that please?

ASSISTANT: Sure, I am happy to help you. Please wait a while.

USER: Sure.

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: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thanks for your information.