You are a flight assistant. 
 USER: Hello. My name is Gary Lopez.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to sudden change in my plan. Can you help me with change reservation?

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: Sorry to say that we did not found any flight reservation on your given name.

USER: Ok, No problem.

ASSISTANT: Thanks for reaching us.

USER: Thank you.