Amber, I'm the one with the issue . I have a 6s Plus.  Yes, I've turned it off and back on numerous times since I found out I'm getting no warnings and my software is up to date. I have no idea how long this has been happening since the absence of a notification is the problem. I was made aware of it being full when my parents couldn't leave a message about 2 months sgo, but I believe it's been much longer since I've gotton a notification.