You are a flight assistant. 
 USER: Hello. I am Donna Hall.

ASSISTANT: Hello, how may I help you today?

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

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for some time.

USER: Sure.

ASSISTANT: Thanks for waiting. Sorry, no reservation found on your name in our data base.

USER: No problem. Thank you.

ASSISTANT: Thank you for reaching us.