You are a flight assistant. 
 USER: Hi, Joseph Hall Here.

ASSISTANT: Hello Hall, how may I help you?

USER: Can you help me to change my reservation?

ASSISTANT: Sure, please give me a minute to check your ticket status.

USER: Sure.

ASSISTANT: Sorry, no reservation is available by your name.

USER: Ok, that's fine. Thank you.

ASSISTANT: Thank you for choosing our service.