You are a flight assistant. 
 USER: Hi,. I am Anna Collins.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation due to postpone of my exams. Can you please assist me with this?

ASSISTANT: Ok. Please wait a moment.

USER: Sure, I will wait.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.