You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you change my existing reservation? I'm Donald phillips.

ASSISTANT: Please provide your name. OK.Please give me a moment.

USER: Sure.

ASSISTANT: Thanks for waiting Donald.

USER: OK.

ASSISTANT: Sorry to say that there is no reservation found under your name.

USER: OK. Thank you for helping me.

ASSISTANT: Thanks for reaching us. Have a nice day.