Sent the wrong TV & now its faulty, wont repair & out of £

OK, I ordered a TV from the Littlewoods website, the wrong set was delivered so I assumed that it was a similar product that was sent and signed for it. 3 and a half years later it has developed a serious fault. Contacted customer service advising that the wrong set had been sent etc, got a reply saying out of warranty & I replied quoting SOGA, under 6 years old & not fit for purpose. A member of the specialist team, (fully aware that the wrong set had been sent and that I had assumed it was a similar TV that had been sent) asked me to get an independent engineers report at my cost, refundable if a manufacturing fault was discovered (and was discovered).

Having heard nothing for over a month I emailed again, and someone has just phoned to say that as it was not the set on the order, there is nothing they can do. They have the serial number of the set which of course will be traceable through their system and will have traceability from the courier who delivered the set. So TV that doesn't work and I'm further out of pocket. Appalling customer service