Hi, will try keep this simple.
Ok I bought my Corrado G60 off ebay in the middle of January, it came with a private registraition that the previous owner was retaining and wasn't part of the deal and clearly listed as such. Also it was listed as having a recent charger rebuild at a stage 4 with documents to prove.
When i collected the car (January 15th 2014) I noticed a rattle coming from the engine under load and a bit down on power but wasn't overly concerned but a day later the piston melted so obviously the rattle I was hearing was detonation. So anyway the previous owner had all the docs so to sort out the plate but never sent anything off so by the time January 31st came round the road tax had expired and therfor could not go any further with it as the car was off the road with no engine and not in a position to tax it. They stated they sent the docs (V5, MOT, and retention forms) but i was in regular conversation with the dvla and they recieved nothing.
Onwards too the middle of April 2014, i've rebuilt another engine and fitted and ready for some road tax. We talk and they say they'll come up with the docs and help me tax it, you know the docs they already stated had been posted to the dvla but miraculously they still have them. I'm easy going so I go with the flow and they come out to mine and we go to my local post office and get tax and then they said they'd send off docs (again) the next day and supply me a tracking number which I was happy with. At this point they also said they couldn't find the charger rebuild proof so I phoned jabbasport with their inscribed serial numbers and they confirmed it as a stage 2 last done 15 years ago.

So the days and weeks go past and no tracking number and dvla still not recieved. Very little feedback from previous owner and then they stopped replying to me at the end of May in which I subsequently just applied for a V5 as was getting sick of running a car which was still not in my name. Never heard nothing back since.
Moving upto today, Dec 8th 2014. I'm not fussed about private plates so advertised it for sale and now all of a sudden they're back in touch wanting to sort it out and get their reg back. Said they'd lost my number previously despite them being able to contact me via two forums (not this one) and also via ebay but no effort was made on their part. Naturally i've told them the score, they want the reg they'll need to pay for it. Plenty chances were given. All a bit strange as was obviously in their best interests to sort it out.
I feel i'm in the right here, not committing any crimes but do feel a bit guilty but that's just the way I am. What would you do? Given I was kind of lied too about charger history which ultimately dictated my purchase. I wouldn't have bothered otherwise.