You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, welcome to flight booking agency. How can I assist you today?

USER: My name is Patricia Lopez. I want to change my existing reservation, because the workshop in New York is postponed.

ASSISTANT: Ok, please allow me a moment while I check for the previous reservation in our data base.

USER: Ok.

ASSISTANT: I appreciate your patience. Patricia, there is no reservation found under your name.

USER: That's ok, thanks for your information.

ASSISTANT: You are welcome. Thank you for contacting us.