Aoto Transmission

2002 V40 was bought used under Volvo extended warranty now has 55000 miles. I had it in when under warranty for a trans flush by Volvo last year and complained about slight slippage and needing to rev to 2000 rpm on first morning shift. They said they found nothing I left it overnight. I knew it was a bit high but today with a big syringe I removed 1.5 Quarts of overfill !! to get it at the "Cold" mark on the stick, temp is 65f motor sat all night. What damage has been done to this transmission, are they known for failure. What will Volvo say about the dealers screw up thats most likely severly shortened my transmission life. To check level I pushed the stick in till it locked, I believe that is the correct way.