You are a flight assistant. 
 USER: Hi. Helen Thomas here.

ASSISTANT: Hello, how may I help you today?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Ok, that is not a problem.

ASSISTANT: Thank you for opting us.

USER: Thank you.