I once took a car for an MOT, and there were two ramps for this purpose. How it happened, I don't know, but when I collected the car, there was list of advisories which I knew couldn't have related to my car. It transpired that the tester had inadvertently put the advisories from the other vehicle being tested onto my car.
When I objected, initially he said, 'Don't worry, they are only advisories, it's not a fail'. When I said I wanted my MOT with no advisories as it should have been, he disappeared and came back with a new certificate with no advisories on it for my car.
I later did a check on the VOSA site, and the advisories were still recorded against my car, and I understand they can't be removed once recorded, even if in error. But how did he manage to print the replacement 'clear' certificate?
I was a bit miffed, as it could have affected any subsequent sale of the car. Plus, it sounded a bit dodgy to me...
Needless to say, I never went back there, but I did manage to sell the car some time later without these 'non existant advisories' affecting the sale.
But it's not the point....
As regards your car, if you want to keep it, I'd push for a partial refund, especially if you bought it on the understanding there were no advisories.
For me, I'd return the vehicle and want a refund. Being a trader, he won't want Trading Standards and VOSA being involved. If he has reprinted the MOT somehow to show no advisories, he doesn't sound a particularly honest trader.
It's not as if there aren't any other Micras for sale....