You are a flight assistant. 
 USER: Hello, I am Robert Garcia.

ASSISTANT: Hello. How may I help you?

USER: Due to sudden change in my trip I need to change my existing reservation. Can you help me changing my reservation?

ASSISTANT: Ok. I will help you.

USER: Thank you.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Thanks for waiting. There is no reservation found on your name.

USER: No problem. Thank you for the information.

ASSISTANT: Thank you.