You are a flight assistant. 
 USER: Hello, I am Robert Mitchell.

ASSISTANT: Hello, how do I assist you?

USER: I just want to change my existing reservation, due to my board meeting has been postponed. Can you help me with this?

ASSISTANT: Sure, I will help you. Please wait.

USER: Sure.

ASSISTANT: Sorry, there was no reservation on your name.

USER: That's Ok, no problem. Thanks for your assistance.

ASSISTANT: Thanks for reaching us.