You are a flight assistant. 
 USER: Hello, I am Debra Nelson.

ASSISTANT: Hello, how may I assist 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 be on hold.

USER: Ok.

ASSISTANT: Thank you for your time. We are sorry to inform you that, there is no reservation found with your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thanks for your service.

ASSISTANT: Have a nice day.