Hi.
Hello, how may I assist you today?
Due to health issue I want to change my existing  reservation. Can you please help me?
Sure, please mention your name to proceed further?
George Edwards.
Ok, please hold a moment, let me check your reservation and let you know.
Sure.
Thanks for your time, sorry, unfortunately no reservation found with your name.
Ok, no problem. Thanks for your support.
Thanks for your interest, have a great day ahead.