You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I provide assistance for you?

USER: I am Samuel Johnson. Due to an emergency, I am unable to catch the flight on the dates which I have reserved, so can you please help me in changing my flight ticket?

ASSISTANT: Sure, I am here to help you. Please wait for a moment I will check your complete reservation details and proceed further with changing your existing reservation.

USER: Sure, take your time. I will wait for your response.

ASSISTANT: Sorry to say this, I did not find any active reservation on your name in my database.

USER: Oh! ok. Thank you for your information.

ASSISTANT: Thank you for reaching us, have a pleasant day.