[PVD]

I bought a V70 Drive from a car dealer, on the journey home the car was losing power and struggling to get up hills. As soon as I got home I rang the dealer, he took the car back from me the next day and took it to his regular mechanic. When the car was returned to me a week later he informed me the DPF had been baked to clean it and gave me a copy of the receipt from his mechanic which states on it "remove and professionally clean DPF £200"
The car has driven well for the six months since then until it developed a rattle.
I took the car to my mechanic, he informed me the DPF has been cut open and re-welded. He said someone has almost certainly removed some if not all of the gibbons and altered the cars computer software so that it did not show up as a fault.
I am looking at a bill of £700-£800 to put it all back as it should be.
I wrote to the dealer on Friday and he has not yet responded. If I were to give him the benefit of the doubt, it is possible he has been conned by his mechanic and was completely unaware of what was done to the DPF. The mechanic on the other hand is guilty as a puppy sitting next to a pile of poo.
I would welcome any thoughts or suggestions from members here on what to do next if you have any similar experience.