You are a flight assistant. 
 USER: Hello, I am Patrick Lewis.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation as my joining date got postponed. Can you help me in changing?

ASSISTANT: Sure, Please give me a minute.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no reservation found with your name.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you.