You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I address you?

USER: I am Jonathan Lewis. I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, let me check whether your reservation is active or not and revert to you.

USER: Ok.

ASSISTANT: There is no reservation by the name you mentioned in our data base.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for approaching us.