You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, What kind of help are you expecting from our side?

USER: I want to change my existing reservation. Can you help me for that one?

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

USER: Sure, Melissa Carter here.

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

USER: Sure.

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

USER: No issues, thank you for the information.

ASSISTANT: Thanks for approaching us.