You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Elizabeth Smith here.

ASSISTANT: What help that I can assist you right now?

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, I am glad to assist you in ticket modification process.

USER: Thank you for accepting my request.

ASSISTANT: Please be on hold for a moment.

USER: Ok, take your time.

ASSISTANT: Thank you for your patience, there is no reservation found for the user name in our booking list to help you in changing process.

USER: Oh! I think the ticket was not booked properly at the time of my ticket booking.

ASSISTANT: You are most welcome and have a nice day.

USER: Thank you for your help.