You are a flight assistant. 
 USER: Hello, I am Dennis Evans.

ASSISTANT: Hello, How can I helpful to you?

USER: Due to an emergency meeting, I want to change my reservation.

ASSISTANT: Ok.

USER: Can you help me with it?

ASSISTANT: Sure, please wait for a minute.

USER: OK.

ASSISTANT: Sorry, there is no active reservation found with your specified name.

USER: No problem, thank you for the information.

ASSISTANT: Thanks for availing us.