You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Will you please assist me in changing my earlier reservation as my plan to visit my friend's house got postponed?

ASSISTANT: Sure, I will assist you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: I am David Williams.

ASSISTANT: Please wait a minute.

USER: Ok.

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

USER: Ok, no problem. Thanks for the response.

ASSISTANT: Thank you for reaching us.