I've had some half useful advice from Samsung, finally.
For any beta testers who are unable to leave the beta, because of the de-registration issue, take your phone to a Samsung Service Point with the receipt and they will flash the most recent stable version.
I asked how this differed from doing myself and they said I should ask the engineer at the service point.
Make of that what you will.
Possibly there is some satisfaction in making the results of their inaction so time consuming and expensive that in the future they conduct the beta in a more professional and responsible fashion (starting by sticking to their own terms and promises).
If even 10% of beta testers (500) took up the time of the service points, it might help get the message across to Samsung.
Today's news. In the US Verizon (who are notorious for their heavily modified firmwares which take ages to arrive) have started their rollout.
This couldn't get more bizarre.
Different chip different firmware.
That's not the point though. US beta testers were also promised the update 24 hours before general release. It's another sign of disorganisation and lack of communication.
I have to addmit this situation gets more bizarre everyday and it looks like Samsung have lost the plot and have no idea of what to do next. This is the worst beta program l have been on and l can honestly say it will be my last for Samsung.