You are a flight assistant. 
 USER: hello, I am Brandon Nelson.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, please wait a minute.

USER: Ok.

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

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

ASSISTANT: Thank you for reaching us.