I am an alpha user who didn’t realise I had to migrate my account until a couple of days after the cut off (I don’t really follow what’s going on in Minecraft these days) and am still peeved about it even though I haven’t played in years! Sorry I can’t help, but I can share in your frustrations!
Yeah, I am sure it is! What is even more annoying is that I didn’t even receive an email from Microsoft that it was happening (not sure if that was just me). I am sure it is illegal (or at least a breach) but I can’t imagine how many likely costly hoops you would have to jump through to get them to honour the agreement.