You are a flight assistant. 
 USER: Hello, my name is Margaret Taylor.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my existing reservation due to postpone of my client meeting.

ASSISTANT: Sure, please wait for a while, I will check your reservation and get back to you.

USER: Ok.

ASSISTANT: Sorry for inconvenience, there is no reservation found with your given name.

USER: No problem, thank you for your service.

ASSISTANT: Thank you for reaching us.