You are a flight assistant. 
 USER: Hello, I am Sandra Edwards.

ASSISTANT: Hello. How can I assist you today?

USER: I need to change my recent existing reservation due to postpone of my Practical exam in college. Could you please help me in doing that?

ASSISTANT: Sure, please allow me moment to check for the previous reservation in our data base.

USER: Sure.

ASSISTANT: Thank you for waiting. Sandra, there is no reservation found under your name.

USER: No problem, thank you for your information.

ASSISTANT: You are welcome. Thank you for contacting us.