You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David Green.

ASSISTANT: How may I assist you at this moment Green?

USER: Due to deal with an emergency case, I am unable to travel that trip. Can you please help me in flight ticket modification?

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

USER: Thank you for your positive response.

ASSISTANT: Please wait a moment to check your previous reservation status.

USER: Ok.

ASSISTANT: When I have checked in our database, there is no reservation showing on your name.

USER: Not a problem with that one, I can reserve another flight ticket for my journey. Thank you for your immediate service.

ASSISTANT: Thank you for reaching to our services, have a great day.

USER: Most welcome.