You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my recent reservation.

ASSISTANT: May I know your name please?

USER: I'm Thomas Walker.

ASSISTANT: Please give me some time to check your details.

USER: Yes sure. Please take your time.

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

USER: Oh!. It's OK. Thank you for your time.