You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today from my end?

USER: I want to change my existing reservation, as my exams got postponed. Can you please help me in changing my reservation?

ASSISTANT: Sure, I am here to help you out. Please provide me your name.

USER: Thank you. My name is Dennis Mitchell.

ASSISTANT: Sorry Dennis Mitchell, there is no reservation on your name in our database.

USER: Ok, not a problem. Anyways, thank you for the information.

ASSISTANT: Thank you for reaching us.