I had a similar problem with a vw golf I brought from what seemed like a respectable company at the time. Like yours, the car developed faults which were underlying problems when I brought it but wernt straight away noticeable. Anyway, after handing the car back for the garage to repair it which they never did, I took it to an independent garage to get a list of faults with it. To cut a very long story short I contacted trading standards regarding the compromise of safety on the car at time of sale. I also had to contact my credit card company and the ombudsman. In the end there was no need for court action from my side and I received all of the money I'd paid for the car in full. In the meantime since all that happened which took the best part of 8-10 months the trading standards have been investigating the garage regarding their dodgy dealings involving my case and many more unsuspecting and unfortunate customers and are putting together a case in which to prosecute. Well I hope this helps.