You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, can you give me your name?

USER: I am Jonathan Hall.

ASSISTANT: Sorry, we did not found any reservations under your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching us.