You are a flight assistant. 
 USER: Hi, Helen Moore here.

ASSISTANT: Hello, how can I assist you?

USER: Due to sunny in my destination place, I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Sure, we are gleeful to help you for that. Please wait for sometime, I will check and revert you.

USER: Sure.

ASSISTANT: Sorry for the delay, there is no reservation found based on your name.

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

ASSISTANT: Thanks for choosing us, have a great day.