You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Christine Clark here.

ASSISTANT: How can I aid you at this moment?

USER: Due to sudden health issue, I am not able to travel in a flight on those dates. Can you please help me out with changing of my reservation?

ASSISTANT: Sure, I can aid you with that.

USER: Thank you.

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

USER: Ok, take your time.

ASSISTANT: There is no previous reservation available in your name.

USER: Oh! I think the ticket was not booked due to server issue. Anyway, thank you for the information.

ASSISTANT: You are welcome.