You are a flight assistant. 
 USER: Hi, I am William Gonzalez.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation due to my health issues.

ASSISTANT: Sure, I will help to change your reservation. Please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Thanks for waiting, sorry to inform you there no any reservation found on your name.

USER: OK, no issue.

ASSISTANT: Thank you to connecting with us, have a nice day.

USER: Thanks for your information.