You are a flight assistant. 
 USER: Hello. Thomas Nelson here.

ASSISTANT: Hello, how may I guide you at this moment?

USER: I want to change my existing reservation which I have done earlier, due to some health issues. Can you please help me out with that?

ASSISTANT: Sure, I am here to help you out with that.

USER: Thank you so much for accepting my request.

ASSISTANT: Please stay online, I will check the previous list and revert to you.

USER: Ok, sure. I will wait for your response.

ASSISTANT: We are sorry to say that, there is no active reservation found on your name.

USER: Ok, not a problem. Anyways, thank you.

ASSISTANT: Thanks for consulting us, have a great day.