You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: Joshua Lopez here. I would like to change my reservation as exams postponed to some other dates, can you please help me with that?

ASSISTANT: Sure, give me a minute.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found under your name.

USER: That's ok, no problem. Thank you for checking out.

ASSISTANT: Thank you for reaching us.