You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I would like to change an existing reservation as my trip got postpone due to heavy rains. Can you help me in changing an existing reservation?

ASSISTANT: Sure, may I know your name?

USER: I am Timothy Williams.

ASSISTANT: Wait a minute.

USER: Sure.

ASSISTANT: Sorry, we could not find any reservation on your given name.

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

ASSISTANT: Thank you for reaching us.