You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Eric Williams, can you help me to change my reservation? Due to some problem.

ASSISTANT: Ok, let me check with your existing reservation.

USER: Yes, please.

ASSISTANT: Eric Williams, no reservation found by your name.Sorry for inconvenience.

USER: Ok, that's fine.

ASSISTANT: Thanks for reaching us.

USER: Thank you for your quick response.

ASSISTANT: Have a great day.