You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you today?

USER: I just want to change an existing reservation due to health issues. Can you help me in change an existing reservation?

ASSISTANT: Ok, please help me with your name?

USER: I made a reservation by this name Stephanie Miller.

ASSISTANT: Ok, please wait I will revert you.

USER: Ok.

ASSISTANT:  Sorry, no reservation was found on your name.

USER: Ok, no problem. Thank you.

ASSISTANT:  Thank you for opting us.