You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Katherine Harris.

ASSISTANT: How can I assist you today?

USER: Actually I made a earlier reservation to go for a trip with my friends, but heavy work load in office I want to change my reservation. Can you help me?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: We are sorry to inform you that we did not find any reservation on your given name.

USER: That's Ok, thanks for your assistance.

ASSISTANT: Thank you for choosing us.