When I worked for a consultancy in about my second year I got a great review. A few days later my manager called me into a meeting and apologised and said the grading had to be reviewed as the country manager wanted it to be lowered. This person didn't know me and didn't know what I was doing. And so it was lowered. This did affect my pay rise I believe, that was all. It did annoy the hell out of me at the time though.

I think my manager made a mistake in letting me know the rating before someone who didn't know me approved it. This probably happens a lot, ratings getting downgraded, and people don't know.