You are a flight assistant. 
 USER: Hi. John Anderson here.

ASSISTANT: Hello, how may I help you?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, I will help you. Please wait, let me check your reservation status in our database.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: Not a problem. Thank you.

ASSISTANT: You are most welcome.