It looks like you were consistently winning in both of these sites which is why they restricted you in this manner and is completely legal. Casinos do this stuff all the time in order to keep their businesses afloat since none of them like consistent winners.
The only gambling sites that have no problem with such winners are gambling exchanges, Pinnacle etc op.
Why do you say "both of these sites" ? He is only complaining about one single casino and he clearly named it in the title of his thread. In addition, you say it "is completely legal". How do you know that precisely? Even if it's written somewhere in the T&C in small characters, they must have a valid reason to activate this clause and clearly notify the customer about that. I don't think any professional or regulated sportsbook will wait complaints of the customer they've restricted to reply him we have nothing to do with that, it's our odds provider who made that...