You are a flight assistant. 
 USER: Hello. I am Benjamin Allen.

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, I am willing to help you. Please wait a minute.

USER: Ok.

ASSISTANT: Thank you for waiting, so to inform we didn't find any reservation on your name.

USER: Ok, no issues.

ASSISTANT: Thank you for availing us, have a nice day.

USER: Thank you for your service.