You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Thomas Moore.

ASSISTANT: How can I help you Thomas?

USER: Can you help me in changing my existing reservation?

ASSISTANT: Sure, please give me a minute.

USER: Ok.

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

USER: Thank  you for the information.

ASSISTANT: Thank you for contacting us.