Unfortunately eBay will not accept assertions of fake from their members. From a commercial viewpoint this makes a lot of sense but is frustrating from this side. As the copyright on the vases is long expired anyone can copy them now but selling them as Whitefriars Drunken Bricklayer (When did the name change from 1967 advertised "Three Cubes"?) is misrepresentation.
The only approach is to report the sellers to Trading Standards. Now here is another difficulty as it will take them some time to react. The last case I submitted to them took several months work to provide a detailed dossier and many more months before that got to the top of the pile, sadly too late the trader stopped. In any case ask your local trading standards. However in the case it is a "one-off" sale the seller can claim to have been unaware - they need to be seen doing it repeatedly to make a deliberate misrepresentation case.
If you buy one believing it to be genuine and realise after buying it that it is a fake, you can go to the seller and point out the problem. If they refuse then you can make a police complaint. You cannot do this if you knew it was a fake before buying it and your involvement in this case lets you out of it. You can try and contact buyers of any fakes and they can make a complaint. eBay might get difficult if they know you are contacting sellers.
Another route is for a network of collectors to locate the source of these fakes, if they are being manufactured in quantity then you could ask the manufacturers to add a mark to the mould.
One possible eBay route is to persuade Caithness glass to use their ownership of the Whitefriars name trademark to get eBay to cancel the auctions under the Vero program. Caithness glass will certainly not do the work but they might be persuaded if a group is organised to police for such abuses - providing they can give give Caithness some assurance that they will not file abusve reports. (Auction does not use Whitefriars name as the maker of the vase, for example.)
Please take care when naming names the first post refers to Jonathan Anderson, a glass artist, in a way that could be taken to suggest he is suspected of making fakes. Mr Anderson does own the original mould and has produced some from that mould and he is legally entitled to do so. You do also mention that these new fakes are clearly recognisable as such. It would be helpful if you add a post clarifying this issue, thank you.
Most likely collectors wil just have to come to terms with the fact that as items reach high value, someone will try and exploit that for profit... way of the world. It is always tough when you first experience a fake but it does have a value... it is a confirmation of the status of the copied item and it hones the collectors skills. Our American friends have had to deal with fake and repro in many of their popular collecting lines, such as depression glass. British glass has few fakes. Webb cameo being one. Paul Ysart paperweights - nearly got away with it, first batch was first class but they got greedy and most were made in a glass factory to a much lower standard but the same designs as the first batch...oops. Monart glass has been faked and probably continues to be in increasing quality. Vasart has had some Ysart style pieces represented as Vasart. Strathearn has had the seals ground off and a Basal ring added, but off course is thicker glass than Monart.
Moulds have always been traded by glass companies, expensive to make so if one company cannot sell a design they sell the mould to another company that thinks it can. Or a company closes down and the moulds are sold off.
Sometimes the better fakes get forgotten. During the circa 70's and 80's a Japanese glassworks made some of the best copies of Galle and for years these were sold by all the major auction house. But if you look on line there is nothing available about these and Mark Chervenka "Fakes & Reproductions" only mentions the Tip Galle, these need the "Tip" ground off to become fake. So where are all these Japanese fakes now? Almost certainly circulating as genuine although possibly not through the big name auction houses.
But Cameo glass and paperweights required high levels of skill to make them. High volume glassware is much more easily reproduced and I would expect to be seeing a lot more as prices rise.
The only solution is knowledge and sharing of information.