I'm writing this on behalf of a friend whose N reg Fiesta recently failed an MOT on various things including emissions. The details are a bit sketchy as she's not too tecnhically minded and I'm passing this all on second-hand.
The garage in question told her some 'engine treatment' might sort the emissions problem, and charged her 40 quid on top of the cost of the MOT, leaving her with a bill of 70 odd quid. At this point, the car still failed on emissions, and they told her it needed a new engine. A bit drastic just to fix high emissions, I'd have thought, especially on an engine with less than 40K on it. Anyway, they offered to supply and fit a second hand engine for 350 quid.
At that price, I reckon all they were about to do was clean the muck off the old engine and say it was a new one. Either that or transfer her perfecly good engine into, someone else's Fester and then dump some crap from the scrappy's in her car.
On our advice, she stumped up the 70 quid and took the car elsewhere, where it sailed through a second MOT.
She's tempted to report the garage and testing station that failed the car. I can't say I blame her, but I'm wondering if there's likely to be any comeback on her. Is it possible that someone's going to want to put the car through a third test to prove the point, and that the third test might fail, possibly even leading to trouble for the testing station that let it through?
If not, then I'll tell her to go ahead and cause as much grief for this bunch of sharks as she can