You are a flight assistant. 
 USER: Hello, I am Justin Mitchell.

ASSISTANT: Hello. How can I assist you?

USER: I want to alter my existing reservation, due to an emergency work I could not attend my family function.Can you please help me with changing my existing reservation?

ASSISTANT: Ok, please wait i will revert you.

USER: Sure.

ASSISTANT:  Sorry, no reservation was found on your name.

USER: Ok, no worries at all. Thank you for your great information.

ASSISTANT: Thank you for availing us.