You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am Rachel Williams.

ASSISTANT: Glad to meet you Williams. How can I help you today?

USER: Can you change my existing reservation which I have done 2 months back.

ASSISTANT: Sure. Hold on for a moment.

USER: Sure.

ASSISTANT: Let me check in our previous records.

USER: It's ok, thanks for checking.

ASSISTANT: Sorry Rachel, there are no flight tickets reserved under your name.

USER: Ok, not an issue. Thanks for your service.

ASSISTANT: Welcome.