You are a flight assistant. 
 USER: Hi. I am Brain Nelson.

ASSISTANT: Hello, how can I help you today?

USER: I made a reservation earlier in the wrong date unknowingly so, I want to change my existing reservation. Can you help me in changing an existing reservation?

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: Ok, not an issue. Thanks for your information.

ASSISTANT: Thanks for reaching us.