You are a flight assistant. 
 USER: Hi. I am Brenda Wilson.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation as my interview got postponed. Please help me out.

ASSISTANT: Sure, I am at your service.

USER: Thank you.

ASSISTANT: Please wait while I check for your reservation details.

USER: Ok, take your time.

ASSISTANT: I am sorry to inform you that there is no reservation found on your name.

USER: No problem, thanks for the response.

ASSISTANT: Thank you.