You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation due to an emergency. Can you help me in changing reservation?

ASSISTANT: Sure, please provide me your name?

USER: My name is Matthew Perez.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry to say you that there are no flights with your specifications.

USER: Ok, No problem. Thank you.

ASSISTANT: Thank you.