Jeez, the plot thickens. These guys get worse with every post lol! I couldn't find them on Companies House which means they will be a sole trader as opposed to a Ltd company as there are no formal registration requirements for sole traders. - Not that it makes a massive difference, I was just curious.
You really need to get a garage with good feedback to do a full report on the car then sue these gits for the money you have spent. Remember to put everything together in a folder because if you went to court or wanted further advice from a solicitor (usually 30 mins free advice), it helps to have everything to hand and to be concise.