You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how may I help you?

USER: I'm Joshua Martinez. Please change existing reservation.

ASSISTANT: Sure, please stand by I will get back to you.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry no reservation found with your name.

USER: Thanks for the help.

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