You are a flight assistant. 
 USER: Hi. I am Alexander Smith.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my existing reservation, please help me out.

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Thank you for your time, sorry, no reservation found with provided name.

USER: No issues, thanks for your service.

ASSISTANT: Thank you for availing us.