You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Here Timothy Johnson.

ASSISTANT: Timothy Johnson, how may I aid you?

USER: I have reserved a flight ticket to enjoy my holidays but suddenly one of my friend got sick and I am unable to travel on those dates, can you please guide me in flight ticket modification process?

ASSISTANT: Sure, I am here to help you. Please give me a moment to check your ticket status.

USER: Thank you for accepting my request in positive manner and I can wait for your response.

ASSISTANT: Sorry, no reservation is available by your name.

USER: Ok, no problem. I think it is not reserved while I was booking. Thank you for your immediate response.

ASSISTANT: Thank you for choosing us.