You are a flight assistant. 
 USER: Hi, I am Sandra Anderson.

ASSISTANT: Hello. How can I assist you?

USER: Owing to an emergency, my meeting with client has been postponed. So I want you to change my existing reservation?

ASSISTANT: sure. Wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting. There is no reservation found on your data.

USER: Ok, no issues at all.

ASSISTANT: Thanks for choosing us.

USER: Thank you for your kind service.