You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Sandra Robinson here.

ASSISTANT: How can I aid you today?

USER: I want to change my previous reservation due some health issues. Can you please help me out?

ASSISTANT: Ok, Please give me a moment.

USER: Ok, take your time.

ASSISTANT: Thank you for your patience, sorry to inform you that there is no reservation found under your name in our database.

USER: It's ok, that is not a problem. Anyway thank you for the information.

ASSISTANT: You are welcome, thank you for opting our agency.