You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: I am Donna Gonzalez.

ASSISTANT: By what way can I support you today?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I will help you with changing.

USER: Thank you.

ASSISTANT: Please wait, Let us check your reservation status.

USER: Sure,.

ASSISTANT: Sorry Donna Gonzalez, Unfortunately there is no active reservation on your name to change it.

USER: Ok, no problem.

ASSISTANT: Thanks for choosing us.

USER: Thanks for your information.