Go back in there with a copy of the Magnuson-Moss act. If they still fight it, lawyer time. They are mistaken.
This is just simply not true. A friend of mine who tracks his GT350R just went through this. He lawyered up and Ford paid out big to replace his engine.I hear people drop the lawyer card here. Unless you currently have a lawyer on retainer, or have a pro bono lawyer best friend, this is going to be pointless. Lotus has WAY more money and Lawyers to mount up a defense, and if for some miraculous reason it gets to the courts, they will stall it into oblivion while your lawyer is still being retained and you are incurring charges by the hour and by every piece of paper they have to review that Lotus will throw their way. Its a common tactic by big companies to wait the little people out till they are broke and cant afford to retain a lawyer anymore.
Its a shitty situation and I would be pissed, but I would have definitely saved all modifications till after the warranty ended. If you did try and sue, what type of service do you think you would get there moving forward? Better off swinging by the Jiffy Lube for that oil change.