Indeed - not only will there be no warranty, I also doubt the legality of what that seller is doing. If these units were bought from Argos, then probably Argos may have something to say about it, and failing that Vestel probably will.
Seeing as the 1.0 twin record software is not an official release, and does not work "properly" (EPG, text problems and lack of freeview playback support from most broadcasters at present, etc) on the current generation 32Mb Digihome boxes, it could be argued that the seller should not be advertising these as Digihome, since the use of the unofficial software could be seen to damage Vestel/Digihome's reputation when not used by somebody who understands it is not an official release. It is my understanding that there may never be an official twin record release for the current Digihome boxes.
Also, imagine all the phonecalls the Argos support number will get from users who cannot figure things out because the manual corresponds to the old software