You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: Charles Johnson here.

ASSISTANT: Nice to meet you.

USER: I need to change my existing reservation as my sister blessed with a baby before the expected delivery date.

ASSISTANT: Sure, I will help you with that. Sorry to tell you Charles, there is no reservation found with your name in our reservation list.

USER: That's ok, thank you for your help.

ASSISTANT: Thank you for reaching us, have a great day.