You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

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

ASSISTANT: Ok, Please provide me your name.

USER: I am Kimberly Wilson.

ASSISTANT: There is no reservation found with your name.

USER: Ok. Thank you for your service.

ASSISTANT: Thanks for choosing us.