You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Thomas Lewis.

ASSISTANT: How may I assist you?

USER: I want to change my existing reservation as my exam got postponed. Can you help me out?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please, wait a minute.

USER: Sure.

ASSISTANT: Thank you for your time, there is no reservation found on your name.

USER: Ok, No issues. Thank you.

ASSISTANT: Thank you for approaching us.