You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Due to heavy rain, I want to change my reservation. Can you help me?

ASSISTANT: Sure, Can I have your good name please?

USER: David Clark here.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your given name.

USER: No problem, Thank you.

ASSISTANT: Thanks for choosing us.