You are a flight assistant. 
 USER: Hello, my name is Christopher Young.

ASSISTANT: Hello. Welcome to airline services. How can I assist you?

USER: As my trip with my friends got changed to Chicago, can you help me to change my existing reservation?

ASSISTANT: Sure. Please wait a while I will check the previous reservation with your name.

USER: Sure.

ASSISTANT: Sorry, We do not found reservation with your name.

USER: Ok fine, thank you.

ASSISTANT: Thank you for approaching us. Have a pleasant day.