You are a flight assistant. 
 USER: Hello. I am Andrew Hernandez.

ASSISTANT: Hello, how can I help you today?

USER: I would like to change my existing reservation due to postpone of my exams. Could you please help me?

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: No worries, thank you for the information.

ASSISTANT: Thanks for reaching us.