Is there any protection when you Buy a Car?

Over two months ago I purchased a car; I examined the car and the registration document and made HPI check on the car.
Everything was O.K; And No Finance was against the car...!
Now somebody called up my house wanting TO TAKE THE CAR AWAY. At the time I was not at home, my wife spoken to them, and she was shocked to hear that there is finance on the car, and it has not been paid....
Please remember the car in question is 拢30000.00. Paid some by check and the rest by Cash.
So my wife took the telephone number of these guys and told them she will pass it on to me to contact them.
I spoke to the man in question, he is from a finance debt recovery company, and then I spook to his manager, and told me they want the car. As two years ago somebody took finance on the car and has not paid it, and since then they sold the car to somebody else and I bought it of the second owner, he had the car for 18 months.
I explained that I have in my hand RAC HPI Check and its all clear, NO finance is registered against the car, and I have a registration documents in my Name.
He said that does not mean anything and we have to take the car, I asked why don`t they send me a letter explaining what is their interest etc... So I can go and see my Solicitor and we will answer any questions they want to know.
He said the law is on their side, so I went to my local police station and reported all this!!! The police officer spoke to them..And they told him the same thing....
Police officer told me it鈥檚 a civil matter and we would have to go to court, but I have to give the car back for know and settle it latter in court.
I walked out of the police station even more angry, bitter and frustrated
Spoke to my solicitor, said we have to wait and see what they do!!!
Please can you advice?

Check with HPI. I just looked on their website and they have a 30,000 guarantee if they give you inaccurate information regarding finance against the vehicle. If you kept all your documentation from the sale of the vehicle (and complied with all their requirements listed) you could make them pay the difference to the lienholder and still get to keep your car.