You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Jonathan Parker.

ASSISTANT: How can I help you?

USER: Mu scheduled examination dates has been postponed.So, I would like to change my existing reservation which is under my name. Can you please help me with that?

ASSISTANT: Ok, please wait for a while.

USER: Sure.

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

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you and have a nice day.