had a callback from the TalkTalk "case manager" who couldn't get a straight answer out of their stores department about whether they bother to test stuff works before accepting it in or sending it out.
he's allegedly got them to promise that they'll be sending me a completely new one to try this time. Whereas the one with the defective ethernet sockets (as far as I could tell) was actually a reconditioned (or not!) return, judging by the label stuck over a label.