You are a flight assistant. 
 USER: Hi, Kenneth Robinson here.

ASSISTANT: Hello,. How may I assist you ?

USER: Due to postponed of my interview, I want to change my existing reservation. Can you assist me with this?

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: I regret there is no reservation by name Kenneth Robinson.

USER: Ok, no problem.

ASSISTANT: Thanks.