You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My name is William Martin. Can you please help me in changing my existing reservation details?

ASSISTANT: Sure, please wait for a while to check your reservation status.

USER: Ok, take your time.

ASSISTANT: Sorry, there is no reservation found by your name.

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

ASSISTANT: Thank you and have a nice day.