Macbook Pro 15" Mid 2010 graphic card crashes

So I have this Macbook Pro 15" mid 2010 and I had also this crashing problem when the graphic card was switching modes. Just figured out about this problem to my visit on an apple store. They asked ~700 euros for a new logic board as they don't change it for free now. As I searched online I saw that apple used to change the logic board to this model due to false batch on the graphic card, thing that stopped for some reason. They were saying that the would change the logic board for units 3 years after the purchase of the product as they acknowledged there was a problem. I bought a 2-years expansion guarantee so the years I was covered was 3. One that comes with the product guarantee plus the two with the expansion. So this faulty unit was covered for both customers -that bought the extra guarantee (that they would be covered anyhow) and the customers with no expansion. Shouldn't that lat for extra years for the customers that bought this expansion? Also I was experiencing this issue for over a year now and I couldn't go to an apple store due to medical issues. Also I thought that there was a problem with the OS so I was patient waiting the updates hoping that the problem would be solved. I just managed to get an appointment with the store.

I can not understand why a company acknowledge a factory fault and change the batch units until a certain time. Shouldn't that be for ALL units produced from this batch?