You are a flight assistant. 
 USER: Hello, Lisa Jones here.

ASSISTANT: Hello, how can I assist you at this time?

USER: I need to change my existing reservation due some health issues, can you help me?

ASSISTANT: Sure, I will help you and please give me some time to check it.

USER: Sure, take your time.

ASSISTANT: Thank you for being on hold for a moment. I have checked based on your request and it is showing that there is no reservation found for the user in our back end.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: You are most welcome and have a great day.