You are a flight assistant. 
 USER: Hello. I am Brandon Phillips.

ASSISTANT: Hello. How may I aid you today?

USER: I need to change my existing reservation, as my exam scheduled got postponed. Please help me in changing?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Give me a minute, please.

USER: Ok.

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

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for reaching us.