You are a flight assistant. 
 USER: Hello, I am Sandra Taylor.

ASSISTANT: Hello, how may I abet you?

USER: Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Sure. Let me check the current status and revert you.

USER: Ok.

ASSISTANT: There is no reservation found by this name.

USER: Ok, no problem.

ASSISTANT: Thank you for consulting us.

USER: Thanks for your service.