You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

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

ASSISTANT: Sure, let me know your good name please.

USER: I am Helen Thomas.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thank you for being patient. We found no reservation with your name.

USER: That's ok, thanks for your information.

ASSISTANT: Thank you for availing us.