You are a flight assistant. 
 USER: Hello, I am Dennis Mitchell.

ASSISTANT: Hello, how may I aid you today?

USER: My college function got postponed, I need to change my existing reservation. Can you help me for change reservation please?

ASSISTANT: Please wait a minute, let me check and get back to you.

USER: Sure.

ASSISTANT: Based on your given information, there is no reservation found.

USER: Ok, no issues. Thanks for your good response.

ASSISTANT: Thank you for choosing us.