You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I be of your help?

USER: I just want to change an existing reservation due to my appointment with client got post pone. Can you help me?

ASSISTANT: Sure, to proceed further may I know your good name please?

USER: I am Richard Miller.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Thank you for waiting. Unfortunately there is no reservation found by your name.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you for opting us and have a good day.