As his complaint is regarding a now dead car and not as to whether the actualy mot test was conducted correctly I dont think vosa will be able to help imo (im also a tester)

The smoke as you've just described it sounds like valve guides/seals....going by a forum post description only that is...altho that dont normaly just come on suddenly tbh. Really the engine is gonna need a strip down then a report done by an independant engineer to assertain the problem and to give you something to stand up in court with. You'll have to weigh up how much the car is worth once back to its previous state against how far you want to take it chap...normaly the general public wins against the motor trade in the small claims courts just because the motor trade already has a very bad rep anyhows.

Stu.