You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you today?

USER: I want to change my existing reservation which is done recently due to some problems, can you please help me?

ASSISTANT: Sure, I am here to help you. May I know the name on which the ticket has been reserved formerly?

USER: Thank you. Sure, my name is Robert Gonzalez.

ASSISTANT: Hold on for a moment. Let me check.

USER: Sure, I will check.

ASSISTANT: Sorry Robert, there are no flights reserved on your given name formerly.

USER: Thank you for your service.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.