You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you at present?

USER: I want to change my existing reservation due to sudden rainfall at my source. Can you please help me with this?

ASSISTANT: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: Sure, I am Margaret Clark.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for availing us.