How bad is the car compared to the images and description of the car in the listing? Is it just a case of badly kerbed alloys and a missing locking wheel nut key? If that's the case you could just drill the locking wheel nuts off, although you would need to buy replacement locking wheel nuts afterwards. However, in the meantime, just put another ordinary wheel nut on each alloy where the locking wheel nut would have gone.
With regards to the kerbed alloys there are several places all over the UK that could do a decent job at refurbishing the alloys. I've always used Lepson's in Gillingham, Kent whenever I've needed alloys refurbished on any of the cars that I've owned over the years as they always do a first class job. By the time you get the alloys back again you'd never be able to tell that they'd ever been kerbed.
If the matter is more serious, such as the car is covered in rust on almost every panel, belches excessive amounts of white smoke out of the exhaust when you start the engine, indicating a head gasket failure, or any other major problem, then contact your card provider and explain that you've been misled into buying a car that was advertised as being in good condition but is far from it. You have one hundred and twenty days from the date of purchase to start a chargeback, so the sooner you get started the better. Hopefully you will be able to get your money back.
Finally, before you committed to buying the car did you run any checks on the car to ensure that it didn't have any outstanding finance on it, had not been recorded stolen or written off, etc? If you failed to do these checks and you subsequently end up finding out that one or more of these factors have been recorded against the vehicle then things could stand to get a lot worse. Always best to do your checks first, then if everything comes back OK go and view the car in person and make sure you're happy with it. That way you're less likely to get screwed over.
