You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Rachel Edwards.

ASSISTANT: How can I assist you Rachel Edwards?

USER: Can you change my existing reservation?

ASSISTANT: Sure, I will help you with this.

USER: Thanks.

ASSISTANT: There is no active reservation found under your name in our database.

USER: It's ok, thanks for your information.

ASSISTANT: Thank you for utilising our service.