You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Unexpectedly the planned trip is postponed by my friend's, so I need to change the details in the previous ticket. Can you help me?

ASSISTANT: Sure, I can help you with that.

USER: Thank you.

ASSISTANT: May I know your name?

USER: My previous ticket is under the name Robert Nelson.

ASSISTANT: There is no previous reservation found on your name.

USER: It's ok, no problem. Thank you for the information.

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