Sorry to hear bout all your trouble mate, But i'd tell them where to stick there car and get your money back, I'd never take a car back thats had that much wrong with it. IMO your going to have nothing but trouble the whole time you have the car, And with it being modded how much stress has the engine had? Probs have engine go pop at some point due to it not being looked after by the previous owner/owners, Good luck tho fella,
Nothing wron with a modded car as long as it's been done right,