You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: I am Kathleen Johnson. I want to change an existing reservation due to sudden change in my trip.

ASSISTANT: Sure, give me a minute.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation found under your name.

USER: No issue, I will choose other alternative.

ASSISTANT: Thank you for choosing us.

USER: Thank you .