You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Gregory Campbell.

ASSISTANT: How can I assist you today?

USER: I am looking for a change reservation service, can you help me with that?

ASSISTANT: Sure, I will help you on that. Please give me a moment.

USER: Sure, take your time.

ASSISTANT: Thank you for waiting. There is no reservation found under your name.

USER: That's fine. Thank you for your help.

ASSISTANT: Welcome, have a great day.