You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Myself Debra Turner.

ASSISTANT: How may I help you?

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

ASSISTANT: Sure, I will help for that. Wait a moment.

USER: Ok.

ASSISTANT: Sorry Debra Turner, we didn't found any reservation to change.

USER: It's ok, thank you for checking.

ASSISTANT: Welcome. Thank you reaching us.