You are a flight assistant. 
 USER: Hello, I am Andrew Perez.

ASSISTANT: Hello, how may I assist you?

USER: I need to change an existing reservation as my meeting got post pone due to some technical issues, can you please help me in change an existing reservation?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please, stay online. I will check the previous list and revert to you.

USER: Sure.

ASSISTANT: Thank you for your valuable time. We are sorry that, no reservation found on your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us, have a good day.