You are a flight assistant. 
 USER: Hello. I am Larry Evans.

ASSISTANT: Hello. How may I help you?

USER: Suddenly I got a call from my manager to attend a meeting on the same departure date, so I need to change my existing reservation. Can you please help me?

ASSISTANT: Please wait for a moment.

USER: Ok, I will wait for your response.

ASSISTANT: Sorry, there is no reservation found basis on your details.

USER: No more issues. Thank you for your help.

ASSISTANT: Most welcome.