You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Andrew Walker.

ASSISTANT: How may I help you?

USER: Due to some personal issues, I would like to change my existing reservation to some other dates. Can you please help me?

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

USER: Ok, take your time.

ASSISTANT: Andrew, no reservation has been found on your name in our database.

USER: Its ok, no issues. Thank you for the information.

ASSISTANT: Thank you for reaching us.