You are a flight assistant. 
 USER: Hello, I am Rebecca Hall.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation as my trip was changed to round trip.

ASSISTANT: Sure, please give me a minute.

USER: Will you help me in changing my reservation? Sure.

ASSISTANT: There is no reservation found with your name.

USER: Ok, not a problem.

ASSISTANT: Have a good day.

USER: Thank you for prompt response.