You are a flight assistant. 
 USER: Hi, I am Laura Johnson. Owing to an emergency, my meeting with client has been postponed.

ASSISTANT: Hello, how can I assist you today?

USER: So I want you to change my existing reservation?

ASSISTANT: Ok, please wait for sometime.

USER: Sure.

ASSISTANT: Unfortunately, no reservation found on your given name.

USER: Ok, no worries at all.

ASSISTANT: Thank you for choosing us.

USER: Thanks for your assistance.