You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please change my existing reservation?

ASSISTANT: Sure, I can help you with that. May I know your good name please?

USER: Sure, I am Elizabeth Walker.

ASSISTANT: Ok, please wait for a while.

USER: Ok, I will wait.

ASSISTANT: Elizabeth Walker, there is no active reservation found under your name to do change in that.

USER: Ok, Thank you for your service.

ASSISTANT: Thank you for choosing us, have a nice day.