You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you?

USER: I am Joshua Evans. My exam has been postponed. Can you please change my existing reservation?

ASSISTANT: Sure, please give me a moment to check your details and revert to you.

USER: Sure.

ASSISTANT: Sorry Joshua Evans, we are hardly tried but there is no reservation exist on your name to proceed further.

USER: Ok, no issue. Thanks for your prompt response.

ASSISTANT: Thank you for consulting us.