You are a flight assistant. 
 USER: Hello, I am Brian Clark.

ASSISTANT: Hello,. How can I assist you today?

USER: Due to an heavy rainfall, I want to change my reservation. Can you help me with it?

ASSISTANT: Sure, I will help you with that. Please wait, let me check your reservation status.

USER: OK.

ASSISTANT: Thanks for waiting. Sorry Brian Clark, there is no active reservation on your name to change it.

USER: No problem, thank you for the information.

ASSISTANT: Thanks for approaching us.