You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER:  I am Jonathan Lewis want to change my reservation due to heavy snow storm. Can you help me in changing my reservation?

ASSISTANT: Please wait for a while, let me check and get back to you.

USER: Ok.

ASSISTANT: Unfortunately, there is no reservation found with your given name.

USER: Thank you for your help.

ASSISTANT: Thank you for visiting us.