and i did contact the seller and he said "All I can think of is the sender has got a knock in transit" great seller btw, fast responce and he gave me a free upgrade from 3.2 Ghz to 3.6Ghz. but im not that good with pcs so i wouldn't know how to fix it my self.
Given that both 3.2Ghz and 3.6Ghz Phenom II X4 processors have been phased out and are no longer being sold he'd probably run out of his stock of the 3.2Ghz model.
I distrust ebay sellers at the best of times, they tend to prioritise big numbers and flashy lights over quality and from your link this chap doesn't seem to be any different. The nVidia 7025 graphics it has for example were released in September 2007 (yes, 2007).
But enough of my moaning, as it's a £300 PC you're probably not particularly bothered about the performance so I'll stick to helping to get it fully working.
The first thing to do is get details of what this display is and how it works as front panel displays aren't a standardised component. If there's no branding on the front of the display then take the side panel off the system (when it's switched off naturally) and see if you can see any model number on the back or whether any of the cables coming from it are loose. I believe these sorts of things tend to be USB devices that connect to the motherboard and are driven by software on the PC so is there any sort of software installed that sounds like it might be related?
If you can take photos of where cables connect as well as any that are unconnected that would be handy to confirm where it expect to get the temperature data from. If there's any going under the CPU cooler (big block of metal with fan attached) then it may be reading the temperature directly.