This is just one way the disc can get warped, my other half had a problem with hers on a brand new ducati, they had a bad batch of discs but replaced under warranty.
New aftermarket parts can usually be better than the original but you have to watch the brake pads that you use with them because they can wear down a lot quicker. This doesn't embeed the performance, it can make it better.
I can't spell so don't take the p*ss! Seriously!
As written by my partner.
Logan
Keep argueing the toss.
I once managed to smash the front rim on an old XJ550 I had (age showing now ) bent the forks,handle bars, tank...hell everything, but when I put it back together the disks were ok.
keep at em mate, good luck
Pete.l
Ask them to show you the score marks in the disc where they claim you dropped it