You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: My name is Jack Johnson. Could you please help me to change my existing reservation?

ASSISTANT: Sure, I can help you with that. Let me check that for you. Jack, I have checked and see that there is no reservation found under your name.

USER: That's ok. Thank you for the information.

ASSISTANT: You are welcome. Thank you for contacting us.