You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I want to change an existing reservation, Can you please help me in that?

ASSISTANT: Sure, may I know your name?

USER: My name is Nicholas Harris.

ASSISTANT: Please give me a moment to check your ticket status.

USER: Sure.

ASSISTANT: Sorry Nicholas Harris, no reservation is available by your name.

USER: Ok, that's not a problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.