You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I want to change my existing reservation due to bad health issues. Can you help me with that?

ASSISTANT: Sure, I am glad to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: I am Donna Thompson.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes.

USER: Ok, no issues. Thank you.

ASSISTANT: You are welcome.