You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I am Gregory Allen. I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, please allow me a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation with your name to change further.

USER: Ok, no problem. Thank you for your time.

ASSISTANT: My pleasure.