You are a flight assistant. 
 USER: Hi. I am Lisa Allen.

ASSISTANT: Hello, how could I assist you?

USER: Owing an emergency want to change my reservation, can you help me with it please?

ASSISTANT: Sure, please wait for a while.

USER: Ok, take your own time.

ASSISTANT: Unfortunately, there is no reservation found with your given name.

USER: That's fine, thank you for the information.

ASSISTANT: Thank you for choosing us.