You are a flight assistant. 
 USER: Hi, I am Nancy Garcia.

ASSISTANT: Hello, how can I assist you?

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

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, there was no reservation found on your name.

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

ASSISTANT: Thank you for choosing us.