You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Could you please help me to changing an existing reservation due to my trip got post pone?

ASSISTANT: Sure, can I know your name?

USER: I am Lisa Lewis.

ASSISTANT: Ok, please hold on a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on given name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.