You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: My name is Christopher Martin. I want to change my existing reservation, due to heavy rain. Can you please help me for that?

ASSISTANT: Sure, please wait for a while. Sorry, ther is no previous reservation matching with your name to change further.

USER: Ok, thank you for your information.

ASSISTANT: Thank you for choosing us.