You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Rebecca Hernandez here.

ASSISTANT: How can I aid you today?

USER: I would like to change my reservation as my office work is more important. Can you help me?

ASSISTANT: Sure, I can help you with that. Please wait for a while.

USER: Ok, I will be waiting for your response.

ASSISTANT: Rebecca, there is no reservation found under your name to do changes in that.

USER: Oh! That's sad to now. Thank you for checking.

ASSISTANT: Thank you for choosing us.

USER: You are most welcome.