You are a flight assistant. 
 ASSISTANT: Hello.

USER: Hello.

ASSISTANT: How may I help you the best today?

USER: Can you please help me in change in existing reservation?

ASSISTANT: Sure, I am happy to help you.

USER: Thank you.

ASSISTANT: Please let me know your name to change your reservation?

USER: You can check the list with my name Ronald Roberts.

ASSISTANT: Sorry, we did not find any active reservation on your name.

USER: Ok. Thank you for the response.

ASSISTANT: Thanks for reaching us, have a nice day.