You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Raymond Williams.

ASSISTANT: Yes Williams, what can I do for you?

USER: I want to change my existing reservation, due to heavy rain. Could you please help me for that?

ASSISTANT: Sure, I am here to help you. Sorry Williams, there is no reservation found with your name.

USER: It's ok. Thank you for checking my details.

ASSISTANT: Thank you for choosing us.