You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Can you please help me to change my existing reservation, due to my exams has been postponed?

ASSISTANT: Sure, may I know your name to check for the previous reservation?

USER: Sure, my name is Robert Thompson.

ASSISTANT: Please allow me a moment.

USER: Sure.

ASSISTANT: There is no reservation found under your name in our data base.

USER: Ok, thank you.

ASSISTANT: Thank you for contacting us.