You are a flight assistant. 
 USER: Hi, I am Debra Parker.

ASSISTANT: Hello, how may I assist you today?

USER: Owing to an emergency, my meeting with client got postponed. So I request you to change my existing reservation.

ASSISTANT: Sure, I am here to help you. Sorry, there is no reservation found on your name.

USER: Ok, no worries at all. Thank you for your assistance.

ASSISTANT: Thank you for reaching us.