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

ASSISTANT: Hello. How can I help you?

USER: Due to sudden changes, I want to change my reservation. Can you please help me with it?

ASSISTANT: Ok, please wait.

USER: Ok.

ASSISTANT:  Sorry, no reservation found on your name.

USER: Not an issue,thank you.

ASSISTANT: Thank you for availing us.