You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Katherine Thompson here. I want to do some changes in the existing reservation because my friends are not able to come on the those dates, can you please help me?

ASSISTANT: Sure Katherine, please wait a moment.

USER: Sure.

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

USER: It's ok, may be on that day I hadn't done my reservation properly.

ASSISTANT: Thank you for choosing us.

USER: It's my pleasure.