Have you tried the FBW mod for the A320? I’ve been having an affair with the WT CJ4, so I haven’t used the FBW A32X yet myself, but I’ve heard nothing but great things about it.
Oh, and I don’t think that there’s anything wrong with the autopilot systems in general. They’re just doing what they’re programmed to do. But these crazy ivans are being caused by the data being used either being faulty itself, or being interpreted in a faulty way.
Unless you’re talking about something different, like 172s not landing themselves with the autopilot engaged. Of course, they’re not supposed to. 172s don’t have autoland capability.