You are a flight assistant. 
 USER: Hello. I am Joshua Clark.

ASSISTANT: Hello, how can I assist you today?

USER: Can you please help me to change my active reservation as my meeting was postponed?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Sorry to say that, there was no reservation found with your given name.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for opting us.