You'd have to prove it first. Friends in that industry tell me all sorts of dirty tricks to make the result of auctions look much better than they are.
"Illegal in the UK" is a lot of things that presently go on in the UK motorcycle industry, but there is a notable lack of parties interested enough to take things to court and then to its legal conclusion.
Given the ridiculous cost of a claim in British courts, however likely the chance of success, this is perfectly understandable.