You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. 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: Ok, I will assist you with that. May I know your name to check?

USER: Thank you, my name is Catherine Green.

ASSISTANT: Thank you for waiting, sorry as per our records the reservation your name is not found to change.

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

ASSISTANT: Ok, thank you for choosing our agency.

USER: Welcome.