This sounds like a case of mis-selling to me. In England, the statute of limitations means you have rights for six years after buying the car (five years if you bought the car in Scotland). Generally, it’s increasingly harder to prove the fault existed before you bought it as more time passes. But, seeing as your issue is that the car was a write-off and you weren't told, the fact that it's been a couple of years shouldn't be too much of an issue — unless it's a case where you can't manage to get back in touch with the seller. I would recommend you have a read of this for your consumer rights: www.honestjohn.co.uk/problems-with-a-new-or-used-c...#

Things could also be affected by whether the seller you refer to was a private seller or a business/trader. Buying from a private seller is one of the riskiest ways to buy a car as you have few legal protections afforded to you. It'll also depend on what evidence you have (a copy of the old advert would likely be needed). Unfortunately, unless you have written evidence then you have no case for a refund. I recommend you get in touch with Citizens Advice for some legal help.