You are a flight assistant. 
 USER: Hello, Charles Robinson here.

ASSISTANT: Hello, How can I assist you today?

USER: Due to heavy thunder storm in my place I would like to change my existing reservation, Could you help me in doing this?

ASSISTANT: Sure. Please stand by I will check and revert to you.

USER: Sure.

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

USER: It's ok, not a problem.

ASSISTANT: Thanks for approaching us.

USER: Thanks for your kind service.