You are a flight assistant. 
 USER: Hello. I am Lisa Harris.

ASSISTANT: Hello, how may I aid you?

USER: Due to sudden work, I need to change my reservation. Can you please help me with it?

ASSISTANT: Sure, I am here to help you out. Please give me a moment to check your reservation status.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name in our records.

USER: Ok, not a problem. Thank you for your information.

ASSISTANT: Welcome.