You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change my existing reservation due to bad weather condition, can you please help me with that?

ASSISTANT: Sure, please share your name for changing reservation.

USER: My name is Sharon Lopez.

ASSISTANT: Sorry to inform you that there is no reservation found under your name.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.