You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: Actually, I want to change my existing reservation due to some health issues, can you please help me in this intent?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Can I have your name on which you reserved earlier?

USER: Sure, my name is Jonathan Brown.

ASSISTANT: Ok, please be hold on for a moment to check your reservation status.

USER: Sure, take your time.

ASSISTANT: Sorry Jonathan Brown, no reservation has found under your name to change.

USER: That's ok, thank you for your appreciable service.

ASSISTANT: My pleasure. Thank you for choosing us, have a good day.