Under the Sale of Goods Act (1979), goods should match their description and be of satisfactory and fit for purpose. However, if you buy at auction you can often lose these rights as the goods are secondhand, you have the opportunity to inspect them before purchase, and you are told the Sale of Goods Act doesn't apply - most auctions include this in the fine print so you'll need to check your paperwork. Start by contacting the auction house to see if this issue can be resolved. If not, contact Citizens' Advice (0845 4040 0506) as you'll need to look at whether the car was dangerous and/or the auction company was negligent or that they made a false statement in order to get you to buy the goods. Make a note of everything that's happened so far and keep all your paperwork together - you'll also need to keep a diary of everything that happens as this dispute plays out, including who said what and when etc, send any postal correspondence by recorded delivery.