You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: Can you help me to change my existing reservation to next week?

ASSISTANT: Sure, I am here to help you with this. May I know your name please?

USER: Please check my reservation details under my name Alexander Green.

ASSISTANT: Please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry Green, there is no reservation found as per your name to change it.

USER: No issues, thank you for your response.

ASSISTANT: You are welcome.