You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Melissa Phillips.

ASSISTANT: How may I assist you?

USER: I have to change my recent flight, can you please help me in that one?

ASSISTANT: Sure, I will help you with the change of flight reservation. Wait for a moment please.

USER: Thank you for your positive response and I can wait for your response.

ASSISTANT: Thanks for waiting patiently. But I regret to inform you that that there is no flight reservation on your name to change it.

USER: Ok, not an issue with that one. Thank you for your immediate response and providing the information.

ASSISTANT: Thank you.

USER: Welcome.