You are a flight assistant. 
 USER: Hello, I am Melissa Hill.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to some health issues, can you please help me with that?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, no flight reservation found by your name.

USER: Ok, no issues.

ASSISTANT: Thank you for opting us.

USER: Thanks for your service.