You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Sarah Hill. I want to change my existing reservation due to bad weather condition, can you help me in changing reservation?

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: There is no reservation found with your given name.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for opting us.