You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Andrew Williams.

ASSISTANT: What can I do for you today?

USER: Will you please change my existing reservation as my scheduled interview got postponed?

ASSISTANT: Sure, please wait for few minutes.

USER: Sure.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.