You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I be your helping hand today?

USER: Can you please help me to modify my existing reservation?

ASSISTANT: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: I am Sarah Jackson.

ASSISTANT: Ok, wait for some time I will check the reservation on your name and get back to you.

USER: Sure, take your time.

ASSISTANT: We are sorry to say that, there is no active reservation found on your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thanks for approaching us.