You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Anthony Walker here.

ASSISTANT: How can I assist you today?

USER: Due to sudden health issue, I am not able to travel in a flight on those date that I want to travel. So, I would like to change my reservation. Can you please help me out with that?

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

USER: Thank you for accepting my request, take your time.

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

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

ASSISTANT: You are welcome. Thank you for reaching us.