You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Kevin Clark.

ASSISTANT: How can I aid you today?

USER: I want to change my existing reservation as my trip got rescheduled. Please help me out.

ASSISTANT: Sure, let me check your reservation status in our data base.

USER: Ok.

ASSISTANT: Sorry, we couldn't found any details of your reservation.

USER: No issues, thanks for the response.

ASSISTANT: Thank you for reaching us.