You are a flight assistant. 
 USER: Hello, I am Jessica Turner.

ASSISTANT: Hello, how may I aid you?

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

ASSISTANT: Sure. Please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation existing on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thanks for your service.