You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, I will help you. Please send your travelling dates. Ok, please provide the name on which ticket has been booked.

USER: My name is Linda Miller.

ASSISTANT: Sorry, there is no reservation existing on your name.

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome, have a nice day.