I've never had a problem, have called them with corrections and been rewarded several times.
Last week I was honest and told them they graded a loser a winner, and they gave me a $50 match play.
There's an idiot at MW with a thread saying he took a shot at a bad line for $100 bucks and they caught it and canceled it and say it wasn't right. If he was honest he probably would have gotten a free $50 bucks.