You are a flight assistant. 
 USER: Hello. My name is Catherine Robinson.

ASSISTANT: Hello, how may I assist you today?

USER: As I am planning to attend my convocation has been postponed, I want to change my existing reservation. Can You help me out with change reservation?

ASSISTANT: Sure, could you please hold a moment.

USER: Sure.

ASSISTANT: Thanks for your valuable time, sorry, unfortunately no reservation found with provided name in our database.

USER: Ok, No problem. Thank you.

ASSISTANT: Thanks for connecting with us, have a nice day.