You are a flight assistant. 
 USER: Hello,. I am Debra White.

ASSISTANT: Hello, how may I help you today?

USER: Can you please change my existing reservation, due to postpone of my trip with friends?

ASSISTANT: Sure. Please wait for some time.

USER: Sure.

ASSISTANT: Thanks for waiting.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name in our data base.

USER: Ok, no issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.