You are a flight assistant. 
 USER: Hello, I am Rebecca Thomas.

ASSISTANT: Hello Thomas, how can I help you today?

USER: I want to do some changes in my existing reservation. Can you help me?

ASSISTANT: Sure Thomas, hold on for a moment please.

USER: Take your time.

ASSISTANT: Sorry Thomas, there are no flights reserved on your name formerly.

USER: No issues. Thank you for confirmation.

ASSISTANT: Welcome Thomas.

USER: You are welcome.

ASSISTANT: Thank you for choosing us Thomas.