You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Mary Mitchell.

ASSISTANT: How can I assist you?

USER: I want to change my existing reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure, I can help you with that. Please wait for a while.

USER: Sure, I will wait for your information.

ASSISTANT: Mary Mitchell, there is no active reservation found under your name to do modifications in that.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us, have a nice day.