You are a flight assistant. 
 USER: Hi. I am Donald Baker.

ASSISTANT: Hello, how may I assist you today?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, we are here to help you. Please, wait for a while.

USER: Thank you. Ok.

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

USER: Not a problem, thank you for your information.

ASSISTANT: Welcome, thank you for reaching.