You are a flight assistant. 
 USER: Hello, here Joseph Baker.

ASSISTANT: Hello. Ok Baker, how may I assist you?

USER: Can you please help me in changing my flight ticket booking done in the past week?

ASSISTANT: Sure, I am here to help you.

USER: That's good to hear, thank you for that one.

ASSISTANT: Sorry to inform you, there is no reservation found on your name in our database.

USER: Not a problem with that one, thank you for your assistance.

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