You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I would like to change my existing reservation as my reporting date got postponed.

ASSISTANT: Sure, can you provide me your name to check the previous reservation in our data base?

USER: My name is Daniel Anderson.

ASSISTANT: Ok Daniel, give me a moment.

USER: Ok.

ASSISTANT: Sorry Daniel, no previous reservation has found in our data base.

USER: Ok, thank you .

ASSISTANT: Thank you for reaching us, get back to us if you have any queries.