You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Michelle Hill. My son is giving a presentation on international competition, but due to some sudden changes, I want to change my existing reservation.

ASSISTANT: Ok, please allow me a minute.

USER: Can you help me with that?

ASSISTANT: Sorry, I haven't found your previous reservation as per your data.

USER: That's ok. Thank you for your response.

ASSISTANT: It's my pleasure, have a nice day.