You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Jonathan Johnson here.

ASSISTANT: How can I assist you?

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: Ok, please wait.

USER: Sure, take your time.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: Oh! I think the ticket was not booked properly at the time of my ticket booking. Anyway, thank you for the information.

ASSISTANT: Ok, thank you for reaching us.