You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: I am Robert Roberts. Due to my health problem I want to change my reservation, can you please help me that?

ASSISTANT: Sure, let me check the current status and get back to you.

USER: Ok.

ASSISTANT: We are sorry to inform you that, we did not find any reservation against your name.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.