You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Mark Smith.

ASSISTANT: How can I assist you at this moment?

USER: I would like to change my reservation as I am leaving for delegates meet, can you please help me out?

ASSISTANT: Sure, I am happy to help you with that.

USER: Thank you.

ASSISTANT: Please be hold on for a moment to check your reservation.

USER: Ok.

ASSISTANT: Sorry Mark Smith, no reservation has found under your name to change.

USER: Ok no problem, thank you for your services.

ASSISTANT: Thank you for choosing us, have  a good day.