You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: Can you please help me in changing my recent booking due to some health issues on the trip dates which we planned?

ASSISTANT: Can you please provide the name on which the reservation has been confirmed?

USER: Sure, I am Joseph Mitchell.

ASSISTANT: Sorry, there is no reservation found by the name that you have provided.

USER: Ok, that's fine, thank you for your quick help.

ASSISTANT: Thank you and have a nice day.

USER: Welcome.