You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you today?

USER: I am Rebecca Brown. I need to change my existing reservation due to postpone of my trip. Can you please help me?

ASSISTANT: Sure, please wait while I find your reservation status.

USER: Sure, I will wait for your response.

ASSISTANT: We are unable to trace your reservation in our database.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.