You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: My name is Gregory Green. I would like to change my reservation, could you help me out?

ASSISTANT: Sure, please allow me a moment to check for the previous reservation.

USER: Sure, take your time.

ASSISTANT: Gregory, there is no reservation found under your name.

USER: That's ok. Thank you for your help.

ASSISTANT: Thank you for reaching us.