You contact the old casino in order to retrieve your prize. It doesn't matter how it's achieved, there is no excuse for confiscating it. It's really a problem for Microgaming, they should have thought of this when they developed the migration system.
The obvious alternative would have been to lock down the tournaments for UK players at an earlier stage in the run up to migration so that no UK players would get caught up in the mess.
The migration of Crazy Vegas to Casino UK screwed up the tournaments, and the account got broken. It then migrated to Roxy palace, and it's still broken, tournaments don't work. In Betway, my ORIGINAL Betway account has somehow been broken, even though it hasn't migrated from elsewhere, I opened it years ago. My alias simply vanished, and clicking on any tournaments does nothing, not even an error message.
I have managed to avoid the mess by not depositing at any casino not confirmed as staying with the UK since mid July. The tournament problem was never fixed at Casino UK, so I wasn't able to compete in the final €20,000, which was just as well because they changed their minds AGAIN only a couple of weeks later, and I would have been unable to finish.
I am STILL getting 30% offers for Royal Vegas, yet this is supposed to have already migrated, so WTF are they playing at
I have had NO email at all telling me what is going on at Fortune Lounge.
It's a damn good job I deserted them in mid July, as if I hadn't, I would be getting jerked around left, right, and centre by all this dithering over the migrations.
Only
32Red and Casino Rewards have seen action from me in September. I have Betway, Roxy Palace, and Spin Casino installed, but they are still broken, and I have heard nothing about the problems being fixed (tournaments) or my migrated accounts being ready to use.