You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Sure. Tell me your name please?

USER: Sure, my name is Dorothy Smith.

ASSISTANT: Please wait.

USER: Sure, I will wait.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no flight reservation on your name to change it.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Anyways, thank you for your service.