You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Could you please help me in changing my existing reservation?

ASSISTANT: Sure, please share your name to proceed.

USER: My name is Catherine Johnson.

ASSISTANT: Please wait for a while to check your details.

USER: Ok.

ASSISTANT: Sorry to say, I did not found any reservation found on your name.

USER: That's ok, thank you for the response.

ASSISTANT: Thank you for reaching us.