You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Barbara Lewis.

ASSISTANT: How may I amend you?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me with this?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please standby.

USER: Ok.

ASSISTANT: Thank you for your time. Sorry, we did not find any reservation in your name.

USER: No issue, I will choose another alternative.

ASSISTANT: Thank you for availing with us.

USER: Thank you.

ASSISTANT: Have a nice day.