You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation due to some technical issues, can you help me out?

ASSISTANT: May I know your name please?

USER: I am David Phillips.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

USER: Ok, no issues. Thank you for your response.

ASSISTANT: Thank you for opting us.