You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Timothy Miller here.

ASSISTANT: How may I serve 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 be on hold.

USER: Ok, take your time.

ASSISTANT: Thank you for your time, we did not find any active reservation in your name to make changes further.

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

ASSISTANT: Thank you for reaching us.