You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I would like to change existing reservation as my sister marriage got postponed.

ASSISTANT: Sure, may I know your name?

USER: I am William Carter.

ASSISTANT: Ok, give me a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no reservation found with your name.

USER: Thank you for your response.

ASSISTANT: Thanks for reaching us.