You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Mark Jones.

ASSISTANT: How can I help you Mark today?

USER: I am planning to change an existing reservation, due to some urgent work. Can you please change my reservation?

ASSISTANT: Sure, I can help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment, I will check your previous reservation status.

USER: Sure.

ASSISTANT: There is no previous reservation available on your name Mark Jones.

USER: That's fine, thank you for your help.

ASSISTANT: Thank you for reaching us, have a nice day.