But they are not refusing to sell to Black people, unless that person is not CORGI registered. It is a private enterprise, and they can sell to whomever they feel fit to sell to.(obviously while adhering to anti-discrim laws)
Just like the pub landlord who can refuse to serve whoever they wish, Screwfix can refuse to serve anyone they wish, and although I disagree with their statement on non-corgi sales, it is completely within their rights to do that.
Alan.