You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I serve you at this moment?

USER: I am Gregory Green. I would like to change my existing reservation, due to sudden changes in climate my tennis match has been postponed. Could you please help me?

ASSISTANT: Sure, please wait for few minutes.

USER: Ok.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.