You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Yes, can you tell me your name?

USER: My name is Samuel Collins.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.