You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, what can I do for you today?

USER:  I am Kevin Clark. I would like to change an existing reservation.

ASSISTANT: Sure, let me check with your previous reservation.

USER: OK,.

ASSISTANT: Sorry to inform you that there is no previous reservation available against your name. Sorry for the inconvenience.

USER: No issues, Thank you for your valuable information.

ASSISTANT: Thanks for reaching out to us. Have a good day.