You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: This is Karen Garcia, from Oakland.

ASSISTANT: How can I support you today?

USER: I have made a reservation for a trip to New York with my friends, for rigging and Unfortunately some of my friends are unable to travel. So, I need you to change my reservation. Can you help me in that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please give me a minute, I will check in the reservation list and revert to you.

USER: Ok, make it in your possible time.

ASSISTANT: Thanks for your waiting. We regret to inform you that, there is no reservation found on your name to change.

USER: That's ok, not an issue. Thanks for your kind information.

ASSISTANT: Thank you for availing us.