You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Charles Wilson here.

ASSISTANT: Is there something I can help you with?

USER: Yes. I want to change my existing reservation to another dates. Because of some work. Can you help me out?

ASSISTANT: Ok. Sure, I am happy to help you. Give me a minute.

USER: Please check. Sure.

ASSISTANT: I am sorry to say that there is no reservation found on your name.

USER: Oh! that's fine. Thank you for your help and support.

ASSISTANT: Thank you for contacting us.